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DoubleD
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Posted - 05/07/2005 : 02:32:30 AM

Issue:
During fireforming, cases suffered partial head separation and bulged heads.
Equipment:
Rifle: 1878 MkII maker mark faded
Cases: CBC 24 Gauge brass shotgun cases reformed to 577/450 rifle cases.
Observations
The three cases presented experienced partial head separation directly adjacent to rim. Brass extrusion occurred in the area of extractor cutouts and adjacent to rim seat directly in front of rim where separation took place.

One case experienced bugled head.

Loads used in failed cases:
Ruptured cases. 70 gr of GOEX Fg topped with a 50/50 mix of CoW and FFg made using Lee 20 gr dipper, a fiber card wad, a grease cookie, fiber card wad, and CBE .462 500gr bullet.
Bulged case. 70 gr by volume of Pyrodex topped off with 50/50 mix of COW and FFg made using one Lee 20 gr dipper, a fiber card wad, a grease cookie, fiber card wad, and CBE .462 500gr bullet.
Examinations:
The separation on these cases occurred directly in front of the rim with soot from gas flow leading back towards the rim. Examination of the interior seemed to indicate the case were of a balloon head design which was confirmed by sectioning. Sectioning does not show any signs of stretching and web thinning normally associated with head separation. The head separation can be seen at the left side of the CBC case in the section photo.
Discussion :
The separation of case heads is not unusual in rifles with excessive headspace or in rifles in which brass has been swapped from one rifle to another. The separation normally occurs in the web area just ahead of the solid head of the case approximately ¼ inch up from the bottom of the case. The head separation in these cases has occurred directly in front of the head. In the CBC case the head is much thinner than a solid head case. The separation is directly in front of the case head which is adjacent to the junction of the chamber and the rim seat.
Some will argue whether the correct terminology for these cases is balloon head. All the literature I found call these cases balloon head or semi balloon head and in the U.S. they have been called that for over 100 years. This discussion is not about semantics or proper nomenclature. Call them what you want. This discussion is to try and determine why these cases failed.

Bertram Solid head left. MagTec Balloon head Right.

Modern Handloading by George Nonte

Handloading by Wm. C. Davis for the National Rifle Association

The Complete Guide to Handloading by Philip B. Sharpe.
Phil Sharpe in his book The Complete Guide to Handloading written in 1937 describes the problems with what he refers to as semi balloon head cases and his description fits almost identically to what is observed in the cases being discussed here. Sharpe discussed a difference in loading density and that the brass had a tendency to upset and flow into extractor cuts. Sharpe also reported that the protruding primer pockets of these cases tended to break off. Sharpe does say that reason the pockets break, was never clearly defined. He also reports problems with balloon head cases was evident in black powder, smokeless powder and low pressure black powder and smokeless powder loads. Sharpe stated these same problems are rarely seen in modern solid head drawn cases. Sharpe finally noted that although as late 1937 the manufacturers of revolver ammunition still used balloon head cases, all rifle cases since the turn of the century were solid head construction.
The balloon head of the CBC case gives it a far greater volume than the solid head case. This is not bad unto itself. Sharpe touches on this in some experimenting he did with 38 SPL cases he found that when loaded with the same bullet, primer and amount of powder, balloon head cases gave lower pressures values than solid head.
Modern standardization of measurements and tolerances provided a means of duplicating rifle chambers from one gun to the next. Standardization made mass production possible and allowed ammunition makers to make ammo that fit every rifle. I have not been able to find any recorded information listing the correct or standard headspace measurements for the Martini Henry rifle chamber at time of manufacturer. Chamber dimensions can be found, but tolerances are not defined. The 577/450 cartridge is a rimmed cartridge and headspace in a rimmed chamber is defined by modern standards as the distance from the datum line to the breech face. The datum line is the surface in the rimmed chamber where the front of the case rim contacts the chamber. Multiple drawings with a myriad of dimensions exist for the various versions of the 577/450 cartridge. The majority of drawings I have observed show a rim dimension of .050 for the Martini cartridge. Applying modern standards there can be up to +0.006 difference in the headspace length and still be serviceable (NO-GO gauge). For battle field dimensions the difference could up to +0.010 (FIELD gauge). See Ackley’s Handbook for Shooters and Reloaders for a good discussion on headspace.
Measurements:
Measurements were taken from several Martini rifles to try and establish a pattern or norm for headspace dimensions. The proper way to take these measurements would have been with a series of precision rim gauges to measure the headspace. Not having such gauges, I utilized several new unfired cases and three original rounds for measuring.

Feeler gauge measurements
The measurements consisted of chambering a round in the gun and closing the breech with a feeler gauge between case head and breech block. This method of measuring does not give a measurement of the headspace of the chamber, it simply gives the gap between cartridge head and breech face or the headspace of the given cartridge. The cartridge rim becomes the GO gauge. Any measurement in excess of 0.006 would exceed the NO-GO dimensions for that particular cartridge case. In excess of 0.010 would exceed FIELD dimensions for the given cartridge case.

Chart
Examination of the CBC cases disclosed the rim seat or forward edge of the rim is not flat. The rim seat surface is angular making it difficult to get a consistent repeatable reference point on the rim. This angular surface affects the cartridge headspace by allowing the cartridge to go deeper in the chamber than it would if it had a flat rim seat and increases head to breech gap.

CBC left, Kynoch right.
In an attempt to chamber the various test rounds in the various chambers it became very evident that there existed a wide variation in chamber dimensions from one Martini rifle to another. Difference in body taper and shoulder shape from one chamber to another in 577/450 Martini’s were noted. The Kynoch and Bertram cases fit in every chamber tried. In some cases the CBC round could not even be forced into the chamber. This is most likely a product of the form die used and has nothing to do with the case itself. After chambering the foil case cartridge in all the chambers, measurements were retaken with different results. It appeared that the foil case due to its thin walls reformed itself to the chamber with the smallest dimensions.

Case Volume:
An empty new unfired Kynoch case, empty new unfired Bertram case and an empty new unfired MagTech case were weighed. Cases were primed with a dead primer before weighing. Each case was then filled with water and reweighed. The cases were dried and filled to the top of the case with GOEX Fg and that charge was weighed. The cases were emptied and refilled by visual observation to the bottom of the neck.

It is obvious that the CBC balloon head case has a far greater volume than the solid head cases.
As a side note Temple and Skennerton reported that the proof load used to test the Martini Henry was 137 grs. of FG and a 715 gr. Bullet.
Firing Tests:
Test #1
Three Bertram new unfired solid head, three Kynoch new unfired solid head and six CBC new unfired balloon head cases were primed with Winchester Large rifle primers and loaded with the traditional LoC load of 85 grs. of Fg, card wad, wax wad, card wad and 500gr. bullet. Air space was filled with 0.6 grs of kapok. After loading of the cartridges the head of each round was checked with a straight edge for flatness. After firing the head flatness was checked again. When loaded in the rifle each round was checked for head to breech face gap. After firing gap measurements where checked.
Test results:
No head separation of any type was experienced. All cases had varying degrees of primer protrusion. One Bertram case and two CBC cases experienced pierced primers. As expected it was not possible to measure a gap between any case head and breech face after firing. All CBC case showed varying degrees of head bulging. No solid head case showed any sign of head bulging. Sectioning of case heads showed no thinning of webs in any of the three cases.

L to R, Bertram, CBC, and Kynoch
TEST #2
Five Bertram new unfired solid head and five CBC new unfired balloon head cases were load with various combinations of the original load that had resulted in head separations.
One Bertram and one CBC case were loaded with 90 grs. GOEX Fg with 0.6 grs. Kapok filler.
Two Bertram and two CBC cases were load with 70 grs. of GOEX Fg, and a 50/50 CoW mix of 19.8 grs. of GOEX Fg and an equivalent volume of CoW*.
One Bertram and one CBC case were loaded with 90 grs. GOEX FFg with 0.6 grs. Kapok filler.
One Bertram and one CBC case were load with 70 grs. of GOEX FFg, and a 50/50 CoW mix of 19.8 grs. of GOEX FFg and an equivalent volume of CoW*.
All cartridges were topped off with a card wad, wax wad, card wad and 500gr. bullet. Remington large rifle primers were used in this test After loading of the cartridges the head of each round was checked with a straight edge for flatness. After firing the head flatness was checked again.
*A Lee 1.3 cc powder dipper was used to make the original 50/50 CoW. FFg was weighed from this dipper and found to deliver 19.8 grs. A volume powder measure was adjusted to hold this weighed 19.8 grs. of powder and that was used to measure the CoW.
All powder charges in all the tests in this report were weighed.
Test results:
No head separation of any type was experienced. All cases had varying degrees of minor primer protrusion. No cases experienced pierced primers. All CBC case showed varying degrees of head bulging. CBC cases using FFg had the most extreme case head bulge.

CBC case head flatness check, before firing.

CBC case head flatness check, after firing.

Same CBC case head sectioned.

Bertram case head flatness check, after firing.

Conclusions
In the U.S. the type case construction used in the CBC cases is called balloon head. (or call it what ever you want) This type of case construction has a long documented history of not be being as strong as the solid head design. The use of this type of case construction was discontinued by makers of rifle ammunition prior to 1900 because of its inherent design weakness.
If excessive cartridge headspace exists, these cases can fail.
Fg and FFg grade black power caused distortion of these balloon head cases. FFG caused extreme distortion.
This rifle has excessive cartridge headspace when used with CBC cases.

Recommendations:
Before shooting any cartridge in a Martini, check the head space of the cartridge to be used. Insert an empty new unfired case in the chamber and make sure it is fully seated. Place a 0.006 inch feeler gauge at the back of the cartridge head and close the breech block. If the gauge is not held by the breech block the rifle should be considered to have failed the NO-GO headspace and it is not recommended to be fired with that case. Repeat the test with a 0.010 inch feeler gauge. If the feeler gauge is not held when the breech block is closed the gun is considered to have failed the FIELD test and should not be fired with that case.
Use solid head cases only.
If you must use balloon head cases use FG powder only. If a brand other than GOEX Fg is used, do test firing and check for head bulging. Head bulging can be checked by placing a straight edge like a steel ruler on the head of the case, and holding the case and ruler up to the light. Tilt the ruler at 45 degrees toward you and look for the light between the head and ruler.

Do not volume load black powder particularly in CBC cases! Weigh all charges and filler on a scale. Do not fill these case to the bottom of the neck with black powder and load.
.
Bibliography:
[Philip B. Sharpe, The Complete Guide to Handloading, Funk and Wagnall Company, Third Edition, Second revision copyright 1937, 1941, 1949, 1952 and 1953.
Parker O. Ackley, Handbook for Shooters and Reloaders, Volume 1, Plaza Publishing, copyright 1962.
B.A. Temple & I.D. Skennerton, A Treatise on the British Military Martini, The Martini-Henry, 1869-C1900 B.A. Temple Publisher, copyright 1983
 

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Discussion Starter #2 (Edited)
Tom in Pittsburgh
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Posted - 05/07/2005 : 08:45:32 AM

WOW -- what a great post.

Thanks.If a guy is handing out $20 dollar bills, there will always be somebody complaining that it isn't two tens...
 

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Discussion Starter #3 (Edited)
Fazer
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Australia
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Posted - 05/07/2005 : 09:25:54 AM
Nice work Douglas, very informative. I hopre people appreciate the time and energy that went into it.
 

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Robert Davidson
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327 Posts
Posted - 05/07/2005 : 11:24:46 AM
Thanks, Douglas. The statement "The use of this type of case construction was discontinued by makers of rifle ammunition prior to 1900 because of its inherent design weakness" says a great deal. And although there will be some who can skillfully reload shotgun brass converted into rifel cases, I shall not be one of them. Safety comes before economy.

richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/07/2005 : 12:26:03 PM
Fortunately with the Martini-Henry, this is not a serious safety issue. The basic action design provides no ready path for hot gas/debris to get in your face, unlike even the M98 Mauser that still allows some blow back through the action….and I have the pitted shooting glasses from a M98 in .243 shooting S&B ammo to prove it. However as pointed out in Skennerton’s books, which is no less true today, the soot/debris blown back into the action plays hell with the smooth operation of the action and is a real pain to clean out. Reformed brass with moderate loads in a rifle with reasonably tight headspace works well. For those with more generous headspace, solid head cases are in order. Of course due care should always be used when shooting any firearm, especially antiques. Frankly it was a fluke that I was wearing shooting glasses when the above described M98 .243 incident occurred. I now never shoot on the range without them….period!

Rich in WV…..savoring life one cartridge at a time!

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/08/2005 : 02:10:40 AM
Good post DD. I'd like to toss out a few points to ponder. First, you say the cases failed "during fireforming". I'm not clear on the process you (or the shooter) was involved in? What about brass extrusion into the extractor cutouts in the test cases? Wouldn't the lack of this phenomonon in your tests (if it didn't take place, you didn't mention it) indicate there was something else, pressure wise, going on with the originals? Next, why the emphasis on "cartridge headspace"? Once fired, any excessive cartridge headspace is fixed, no? As long as you segregate your cases by rifle, watch your resizing technique and don't attempt to fully resize the neck/shoulder, potential problems are minimized. I don't disagree with your words of caution and that the CBC brass should be reserved for rifles with closer tolerances but isn't the problem really rifle headspace? Just a few things off the top of my head. More discussion should be welcomed by all. Thanks.Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....

John Wallace
Gunboards.Com Gold Star Member


3488 Posts
Posted - 05/08/2005 : 02:56:21 AM
There is certainly a lot of very informative detail there. But the solution to the problem is to start with your forming die a little too high, and lower it a little at a time, until you are positioning the case shoulder as far forward as will allow your case to chamber in the specific rifle with which it will be used. I think the problem would be avoided or much lessened if this was done initially and in every successive reloading of your now chamber-shaped cases. This isn't a lot of help if you need to use the cases in a number of differently chambered rifles, of course. I think you have to use solid-head cases for this puirpose, and conclude that saving money has to cost you something.'I know what war means. I have been with the armies of all the belligerents except one, and I have seen men die, and go mad, and lie in hospitals suffering hell; but there is a worse thing than that. War means an ugly mob madness, crucifying the truth tellers, choking the artists, sidetracking reforms, revolutions and the working of social forces'.

John Reed

DoubleD
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South Africa
1829 Posts



Posted - 05/08/2005 : 11:11:15 AM
quote: Originally posted by MCQueenie

Good post DD. I'd like to toss out a few points to ponder. First, you say the cases failed "during fireforming". I'm not clear on the process you (or the shooter) was involved in?
Brand new cases never been fired before. Just die formed and fired for the first time. I debated over using the word when I was writing, but I though everyone would know what it meant. Guess I was wrong.



quote: What about brass extrusion into the extractor cutouts in the test cases? Wouldn't the lack of this phenomenon in your tests (if it didn't take place, you didn't mention it) indicate there was something else, pressure wise, going on with the originals?

Yes it does signify something different went on. I didn't load or fire the original cartridges that failed. The cases that failed didn't come from the same box that failed. I carefully weighed each charge in the cartridges I built. I know the 50/50 CoW was constructed by using Lee dippers. Richard can comment here, but I believe the main charge was also constructed using Lee dippers. I didn't check those dippers and that could explain some difference. If you go back and read my report you will see my reference to passage in Sharpe’s book. "Phil Sharpe in his book The Complete Guide to Handloading written in 1937 describes the problems with what he refers to as semi balloon head cases and his description fits almost identically to what is observed in the cases being discussed here. Sharpe discussed a difference in loading density and that the brass had a tendency to upset and flow into extractor cuts."



quote: Next, why the emphasis on "cartridge headspace"? Once fired, any excessive cartridge headspace is fixed, no? As long as you segregate your cases by rifle, watch your resizing technique and don't attempt to fully resize the neck/shoulder, potential problems are minimized. I don't disagree with your words of caution and that the CBC brass should be reserved for rifles with closer tolerances but isn't the problem really rifle headspace?

"Modern standardization of measurements and tolerances provided a means of duplicating rifle chambers from one gun to the next. Standardization made mass production possible and allowed ammunition makers to make ammo that fit every rifle. I have not been able to find any recorded information listing the correct or standard headspace measurements for the Martini Henry rifle chamber at time of manufacturer. Chamber dimensions can be found, but tolerances are not defined. The 577/450 cartridge is a rimmed cartridge and headspace in a rimmed chamber is defined by modern standards as the distance from the datum line to the breech face. The datum line is the surface in the rimmed chamber where the front of the case rim contacts the chamber. Multiple drawings with a myriad of dimensions exist for the various versions of the 577/450 cartridge. The majority of drawings I have observed show a rim dimension of .050 for the Martini cartridge. Applying modern standards there can be up to +0.006 difference in the headspace length and still be serviceable (NO-GO gauge). For battle field dimensions the difference could up to +0.010 (FIELD gauge). See Ackley’s Handbook for Shooters and Reloaders for a good discussion on headspace.

The purpose of the brass case is to seal the bore to the gases when the cartridge is fired. In order to assure the chamber and brass are compatible standards must be established so every cartridge case for a given caliber will fit in every chamber for a given caliber and not rupture when fired. The modern standard is 0.006 NO-GO and 0.010 FIELD. This means an absolutely perfect RIMMED chamber will have a gap 0.050 from rim seat to breech face. An absolutely perfect rimmed cartridge will have a rim thickness of 0.050. It doesn't work that way in the real world. It is very difficult to work to the level of precision. There are too many variables. There is a need tolerances. The modern 577/450 Rimmed chamber tolerance is plus 0.005. The distance from the rim seat to the breech face can be up to 0.055 and still be with in tolerance or Headspace.

Cartridges also have a tolerance or head space that corresponds to the headspace dimension in the chamber. Modern 577/450 cartridges have a rim measurement of 0.050 with a tolerance of minus 0.010. So the rim thickness on a rimmed cartridge can be no more than 0.050 but no less than 0.040.

So if you have a chamber that has a maximum 0.055 chamber and refuses to accept the 0.056 NO GO gauges it would still be with in acceptable headspace limits. If you had a cartridge with a rim thickness of 0.040 it would be within acceptable cartridge head space limits. But if you placed that cartridge in this chamber and measured the gap between head and breech face you would have a gap 0.015. Out of headspace? Nope, with in allowable limits! that is why I check head to breech gap. Look at my chart you won't find any of the case measured had a gap of 0.0150.

Would you get protruding or pierced primer, most likely. Would you get case failures in solid head cases? Not likely the first shot but brass life might be short.

But in balloon head shotgun cases with the tapered rim you will definitely get some sort of failure. First the taper acts to make the rim even thinner, allowing the case to seat even deeper into the chamber and expanding the head to breech gap.

When fired the case expands and fills the chamber. The thin areas expand first. The gap between head and breech face must be filled and the thin case head does not have the strength to resist the expansion and in my test the head bulges. The solid head cases have a greater strength and are better able to resist expansion.

My test clearly shows the gap between cases head was being filled up firing. I believe that even in the solid head cases with the use of an optical comparator some head bulging could be detected. But more importantly the overall length of the solid head cases was increased as the case body stretched to fill the gap.

To say after firing the headspace is fixed, is not quite correct. What is correct is to say that the dimensions of the fired case is fixed to the particular chamber in which it was fired. That is why you shouldn't and sometimes can't interchange cases from one gun of the same caliber to another.

This brings me to John Wallace's comment. Great minds think alike John. The procedure that John describes is to change the headspace reference point from the rim to the shoulder. It is a common practice in single shot rifles. First rimless cartridges head space in this manner and the technique can be applied to rimmed and belted cartridges. If done as John described it works well and brass life should be fairly normal. But there is one other condition that John overlooked and I almost did also.

I was talking with RichardWV (this is his rifle, if it matters) about the test I was planning, and discussing setting the cases up to headspace on the shoulder. I explained as John did about the method and Richard asked if the would make a gap at the front of the rim. Yes of course it will. Richard asked well since the rim on the out side of the case is the same thickness as the head on the inside isn't that going to place a very thin case wall over the gap between the rim and chamber rim seat? He very right!

One of the problems just briefly mentioned in my report was how tight these cases were going in the chamber. I made sure the cases I fired were fully seated before firing. If Richard during his firing didn’t get the cases as fully seated as I did that could explain why they blew out on him and not on me.

I suppose in all honestly I should have used the same reloading dies as Richard to do my test…(Richard is now thinking how many more cases is this going to cost him)

The method John describes is a good method to correct headspace, but only if you use solid head cases. Using balloon head cases places a very thin section of wall over an unsupported section of chamber and is asking for trouble.

I have stated that headspace is a factor in this issue. To repeat this rifle has excessive head space. To say that excessive head space is the sole cause of this failure is a smoke screen.

I do not have a vested interest in seeing these cases fail I want them to work. I much prefer spending $16 for 25 cases than $90 for 20 cases. I not laying any smoke screens to make you think they are any safer or more dangerous than they are. I am not expounding some new revolutionary theory. There is a well documented history regarding this case design. I am urging caution, and that is all!
DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.
Edited by - DoubleD on 05/08/2005 11:18:16 AM

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/08/2005 : 1:11:04 PM
Thanks for the clarification DD. Rereading this post I see no direct mention of the rifle's headspace. Your post tends to focus more on the brass. Just giving the rifle's headspace a quick mention as "excessive" without providing some indication as to how excessive is not very good "science" IMHO. Also IMHO your cartridge/rifle measurements are not very reliable. You used full cases where shoulder contact can come into play and skew your results. I'm pretty sure that is where some of the wide variations between cases and rifles occur. It must also explain why Bertram brass, with its thicker rim, measures equal to or within .001 and in one case .002 MORE than the Magtech in some rifles unless the contention that the rim design of the Magtech is a contributor is not correct.Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....

gert10
Gunboards Super Premium Member


456 Posts
Posted - 05/08/2005 : 1:51:24 PM
Mcqueenie,
I think this is where the remark as to the Magtech case dimensions comes into play: "In some cases the CBC round could not even be forced into the chamber. This is most likely a product of the form die used and has nothing to do with the case itself."
I presume that in some chambers, the Magtech brass (which probably had the shoulder a bit further forward, a bit bigger diamter somewehere or whatever) did NOT headspace on the rim, but on the shoulder.
In my mind, not that important an issue - the big issue is the amount of brass exposed and unsupported, and its solidity. Of course, this is a rifle issue, but the Magtech brass appears less 'forgiving' of the condition than the other makes.
Bottom line still remains the same, however - check the condition on your rifle and act accordingly. And know you are lucky because the design won't blow gases back straight in your face in the event of a case rupture...

DoubleD
Moderator


South Africa
1829 Posts



Posted - 05/09/2005 : 12:00:32 AM
quote: Originally posted by MCQueenie


Thanks for the clarification DD. Rereading this post I see no direct mention of the rifle's headspace. Your post tends to focus more on the brass. Just giving the rifle's headspace a quick mention as "excessive" without providing some indication as to how excessive is not very good "science" IMHO. Also IMHO your cartridge/rifle measurements are not very reliable. You used full cases where shoulder contact can come into play and skew your results. I'm pretty sure that is where some of the wide variations between cases and rifles occur. It must also explain why Bertram brass, with its thicker rim, measures equal to or within .001 and in one case .002 MORE than the Magtech in some rifles unless the contention that the rim design of the Magtech is a contributor is not correct.
There seems to be a fixation on the headspace of this rifle and it is argued that it and it alone is responsible for the failure of these cases. That, excess headspace in this rifle contributed to the failure is not disputed. The fact that for over 100 years the weakness of this design has been well known and documented seems to be ignored. This weak design simply exaggerated the failure. When subjected to equal loads the damage to the balloon head cases was greater than the solids. That's what this report details.

But to satisfy everyone’s curiosity let just address the questions.



quote: Rereading this post I see no direct mention of the rifle's headspace. Your post tends to focus more on the brass.

I can see how you could come to this conclusion. The answers to your questions are in the report. In the report and in the chart, the rifle being tested is the MK II. I stated that at the beginning of the report. I should have made that clear on the chart. There are a series of measurements giving the cartridge head breechblock gap with various cartridges. But those are not the numbers you seem to be seeking. So here are the questions I think you want answered with the answers found in my report in quotations.

Q. What is the distance from the datum line to breech face of the rifle in question?

A. Not directly measured. “The proper way to take these measurements would have been with a series of precision rim gauges to measure the headspace.
Not having such gauges, I utilized several new unfired cases and three original rounds for measuring.”

Q. What is the headspace of the MK II.

A.” I have not been able to find any recorded information listing the correct or standard headspace measurements for the Martini Henry rifle chamber at time of manufacturer. Chamber dimensions can be found, but tolerances are not defined.”

There are modern standards but those standards were not in effect during the time the MH was being made.

The correct way to measure the chamber would have been with precision gauges. There are gauges meeting modern specifications. But what were the specifications and what were the GO/NO-GO/ FIELD dimensions for the MK II when it was made? I don’t have that information. I have been looking for it for some time. So an alternative method was sought and that was to measure case head to breech face gap.



quote: Just giving the rifle's headspace a quick mention as "excessive"

without providing some indication as to how excessive is not very good
"science" IMHO.
You are quite right I was subjective.

I could have given you the measurement of how much the primer protruded or
the head bulged but I don’t own an optical comparator to take the measurement.



quote: Also IMHO your cartridge/rifle measurements are not very reliable. You

used full cases where shoulder contact can come into play and skew your results. I'm pretty sure that is where some of the wide variations between
cases and rifles occur.
If I had an ax to grind, your opinion would be quite right. But I don’t! I have no reason to see these cases fail. I want cheap cases to buy just like everyone else. I’m not selling solid cases and I’m not hoping the competition fails. I don’t have a vested interest in seeing these cases fail as do other who take exception to me reporting a 100 year old fact.



quote: ...your cartridge/rifle measurements are not very reliable… where some of

the wide variations between cases and rifles occur.
Subjective statements.

If I were trying to skew results I certainly wouldn’t have posted such easily verifiable measurements. Also I would not have posted measurements that show any variation not supporting my imagined position.

Additionally if I wanted to skew the measurements I would have included the measurement for two MK IV’s that don’t appear on the list. Both rifles had
dings in their rims and made repeatable seating impossible.

“In an attempt to chamber the various test rounds in the various chambers it became very evident that there existed a wide variation in chamber
dimensions from one Martini rifle to another. Difference in body taper and
shoulder shape from one chamber to another in 577/450 Martini’s were noted.”

If I detected any interference of any type that prevented the case from fully seating, I reported it. I made every effort to assure the cases were fully seating. Measurements were checked and rechecked before recording. If I didn’t get what I considered a proper fully seated measurement, I noted it. It is possible the measurement were interfered with by chamber shape. If the measurements were off to due to chamber interference it doesn’t manifest itself as significant on the chart and certainly doesn’t seem to be great enough to make the case fail. (My opinion.)

“The Kynoch and Bertram cases fit in every chamber tried. In some cases the
CBC round could not even be forced into the chamber. This is most likely a
product of the form die used and has nothing to do with the case itself. After chambering the foil case cartridge in all the chambers, measurements were retaken with different results. It appeared that the foil case due to its thin walls reformed itself to the chamber with the smallest dimensions.”

Further the load test seems to make all these measurement irrelevant. The measurements across the board show that the test rifle had excess headspace and that is repeated through out the report. When the rifle is fired both style cases show evidence of excess head space-protruding primers. Only the balloon head case has a bulged head. This is not something that could be predicted by measurement.

Those who are selling these CBC cases don’t want to discuss that. They chose to change the topic and conveniently ignore the 100 year old history of the weakness of this design.



quote: It must also explain why Bertram brass, with its thicker rim, measures

equal to or within .001 and in one case .002 MORE than the Magtech in some
rifles unless the contention that the rim design of the Magtech is a
contributor is not correct
Kynoch had the thicker rim.

You are right in questioning these measurements. There is something going on. But I fail to see anthing that would make one case bugle its head and another not. Perhaps the most interesting is the measurements of the old original cartridges. They are extremely consistent in my opinion. The modern cases are not.

The front of the CBC case has no flat surface to bear against the full diameter of the rim seat.. Where the rim actually seats is dependent on the diameter of the chamber at the datum line. The greater the diameter, the deeper the cases will seat.

Now here are the conclusions I drew from my tests. Do you see anything in my tests that invalidates these conclusions. Can you provide any information to contradict these conclusions?


“Conclusions

“In the U.S. the type case construction used in the CBC cases is called balloon head. (or call it what ever you want) This type of case construction has a long documented history of not be being as strong as the solid head design. The use of this type of case construction was discontinued by makers of rifle ammunition prior to 1900 because of its inherent design weakness.

“If excessive cartridge headspace exists, these cases can fail.

“Fg and FFg grade black power caused distortion of these balloon head cases.
FFG caused extreme distortion.

“This rifle has excessive cartridge headspace when used with CBC cases.


“Recommendations:

“Before shooting any cartridge in a Martini, check the headspace of the cartridge to be used. Insert an empty new unfired case in the chamber and make sure it is fully seated. Place a 0.006 inch feeler gauge at the back of the cartridge head and close the breechblock. If the gauge is not held by the breech block the rifle should be considered to have failed the NO-GO headspace and it is not recommended to be fired with that case. Repeat the test with a 0.010 inch feeler gauge. If the feeler gauge is not held when the breechblock is closed the gun is considered to have failed the FIELD test and should not be fired with that case.

“Use solid head cases only.

“If you must use balloon head cases use FG powder only. If a brand other than GOEX Fg is used, do test firing and check for head bulging. Head bulging can be checked by placing a straight edge like a steel ruler on the head of the case, and holding the case and ruler up to the light. Tilt the ruler at 45 degrees toward you and look for the light between the head and ruler.

“Do not volume load black powder particularly in CBC cases! Weigh all charges and filler on a scale. Do not fill these cases to the bottom of the neck with black powder and load.”
DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.



richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/09/2005 : 12:07:23 AM

There are a number of variables with the ammo that were not fully explored in DoubleD’s testing. Since he has the severe disability of having a full time job
, is not pulling down a big check for test and evaluation of case construction, doesn’t have a ballistics lab and lamentably doesn’t have a range out his back door, I think he has done a admirable job at the expense of significant personal time in working out the considerations and presenting them in a professional manner….with graphics even (hey we former Defense types love graphics, fills up pages, looks pretty and saves on reading).


My first case head separations occurred using paper patched bullets (.450 diameter Buffalo Arms 475 grains, wrapped to about .463 using their paper for patching). DoubleD was using grease groove bullets, which I’ve convinced myself generate lower pressures in the same diameter. The same load had been used for a period of time in one of my MK IV rifles without any high pressure signs, but were new to the subject MK II, which mechanically appeared to be in very good condition…with a very nice bore.

Not all of the cases split. A few looked more or less normal, a few had a large head bulge with primer pocket leakage, and a few split. How firmly they were seated may certainly have been a factor (breach closed being my only criterum up until then). The first split came about the fourth or fifth shot. After 3 splits I quit, which was probably around 9 or 10 rounds total. The point here being that the bulges/spits got worse as the session progressed, which to me indicates that either heating or fouling was also a contributing factor resulting in the rate of failure increasing with use. At DoubleD’s urging, my next attempt involved grease groove bullets that he generously provided. I was out of BP Fg, and substituted Pyrodex Select (BP is not readily available in my immediate area). This ammo was better, but still had significant case distortion and a split. At this point I turned the investigation over to DoubleD as a “learning opportunity.”

For now, I’ve ceased shooting the subject rifle. I’ve got others that digest MAGTECH cases just fine, with some of my early cases now having reached 10 reloadings. Other than for the subject rifle’s split case heads, all of my case losses to date involve defective cases splitting at the defects (shoulder and neck) I created while learning to form them. That’s solely my learning curve and not a reflection on the brass. One thing I have learned however is that forming folds and dimples do not necessarily ruin the case, since some of my early cases with defects continue to hold up well. As a side note, I’ve got my reject rate down to one or less per box of 25 shells formed. If I showed more patience on stage 3 of case forming I probably could lower it further, but patience is not a key descriptor of my personality type.

Based on the fact that I’m now out of bullets for loading, I can safely say that I’ve fired somewhere around 750 rounds of 577-450 MH. During Graf’s last sale I picked up a full case of brass shells and plan on continuing to use them to form MH and Snider cases. My price per case comes to about 42 cents, so continued use is economically compelling. I should point out that if the MH was designed such as to allow a face full of hot gas and debris, I might think a little longer on it. Fortunately, it is not. Over recent months I’ve gained a real appreciation for the Martini design as a strong, safe and reliable action.

If I had been using solid head cases, DoubleD’s tests show that it is unlikely that I would have noticed any issue with the subject rifle. However it is also true that if I was using solid head cases I would have probably only bought 20, shot the rifle a few times and then retired it to the back of the rack without having gotten hooked on the Martini action.

Today was a bit of a milestone for me. Two days ago I shot a test load in a MK IV of mine, which resulted in a very tight group with 4 of the holes touching. Of course after shooting 8 inch (and up) groups for the past 5 months the immediate question was whether this was a fluke (my immediate assumption) or a repeatable decent performance. Yesterday I loaded up 25 more of the same load and hit the range this afternoon. Even though the wind was averaging over 25mph, the first group was a respectable (at least for me) 8 inches….The next 4 groups were all under 4 inches
(this load must like fouled bores). Assuming I can purchase more of the same bullets (RCBS 465-480-FN) from Western Bullet Co., I think I finally have a load I’m willing to shoot in public. While I will continue to work up an “authentic” paper patched load that I can consistently keep in the black, with me the ability to hit the target carries equal weight with authenticity. Without the assistance, prodding and moral support from DoubleD, I would have dismissed these rifles as inaccurate relics of the 19th Century deserving of a place of honor on the wall, but not on the range. Thanks Douglas!



Rich in WV…..savoring life one cartridge at a time!

DoubleD
Moderator


South Africa
1829 Posts



Posted - 05/09/2005 : 12:29:25 AM
quote: Originally posted by richardwv



I was out of BP Fg, and substituted Pyrodex Select (BP is not readily available in my immediate area).
Not a true statment...Back Creek Gun shop is a major distributer and is about 10 miles up stream...but then you didn't know that then!!
DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.


richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/09/2005 : 01:20:44 AM

DoubleD, as you know I load down here in N.Va. While Back Creek Gun Shop may still be the closest source (or Spark’s in Martinsburg), both are more like an hour and a half from home, which is not exactly spur of the moment shopping. Conversely, for Pyrodex or Triple 7, I've got sources within 15 minutes of here. It is a shame that local counties have essentially legislated BP out of the retail chain as a dangerous explosive that somebody may make a bomb out of (Fairfax and Arlington's excuse). I don't suppose they are going to legislate fertilizer and diesel fuel out of existence....which of course has actually been used for that purpose. My mistake was thinking of BP in the same terms as other powders I use for reloading, which with the cavernous MH case just isn’t so. Five pounds is the more realistic purchase quantity.

Rich in WV…..savoring life one cartridge at a time!

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/09/2005 : 12:13:53 PM

Thank you Rich. Your posts add a needed perspective to the overall picture. Thanks again DD for taking the time to reply. I'm asking a lot of questions because the clearer the water the easier it is to see the bottom. I know you have stated your intentions many times already so forgive me for being a suspicious and cynical old (middle aged maybe ? ) fart. All this discussion makes me want to go out and "bust some caps". I think I'll do just that.
Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....Edited by - MCQueenie on 05/09/2005 12:27:12 PM

DoubleD
Moderator


South Africa
1829 Posts



Posted - 05/10/2005 : 01:05:18 AM
quote: Originally posted by richardwv


There are a number of variables with the ammo that were not fully explored in DoubleD’s testing.
Richard, it appears MCQueenie thinks you have exposed me as a fraud with your statement.



quote: Originally posted by McQueen! on EZ board


I've had mixed feeling about this whole deal. DD's caution is warranted without a doubt. However, the devil is in the details and IMHO some very important details did not receive the attention deserved as it affected the overall perception of what is going on. Coyote' is correct, again IMHO, in insisting that the rifle in question's headspace is paramount to the issue. Its entirely possible that had solid head cases been used they would have separated too. If that were the case, well..... However, we cannot ignore the potential shortcomings of the Magtech design. Those shortcomings may have contributed. Read the thread over at Gunboards. Richardw, the rifle owner, provides a more "even keeled" perspective on the matter, I think. In all fairness, considering the business dealings of a fellow board member and valuable contributor to the community, the "caution" could have been stated a little more cautiously. Again, just MHO.

quote: However, the devil is in the details and IMHO some very important details did not receive the attention deserved as it affected the overall perception of what is going on.
Care to define what details you are talking about?




quote: Coyote' is correct, again IMHO, in insisting that the rifle in question's headspace is paramount to the issue.
Coyote is absolutely right. Headspace is important and that issue is addressed through out my report. Instead of ignoring headspace since I don't have available the correct gauges, I used alternate methods for determining that head space was an issue.




quote: Its entirely possible that had solid head cases been used they would have separated too.
Read the report again. Solid head cases were used through out the tests in the gun that had the head separation and that is in the report. Solid head cases did not separate. That is in the report. Solid head cases had protruding primers a classic sign of excessive headspace supporting the conclusion that the rifle has excessive headspace. That is in the report.




quote: Richardw, the rifle owner, provides a more "even keeled" perspective on the matter, I think.
What does Richard say that I don't?




quote: In all fairness, considering the business dealings of a fellow board member and valuable contributor to the community, the "caution" could have been stated a little more cautiously. Again, just MHO.
Huh, business before safety? I do not believe for one second Coyote puts business before safety. But he does have a vested financial interest in the success of the product which in my opinion make his position just a bit biased. In plain language he has a conflict of interest.

You seem to make it appear that Coyote’s motive in objecting so loudly is business. What motive do you lay on me for wanting to see them fail?

That he is valuable contributor to the community, is without question. If there is any one person who has influenced my knowledge and drive in regards to the Martini, it has to be Coyote. He sparked my fervor. And I will be forever grateful to him for that.

Why would anyone object to the repeat of a safety warning to use caution with a product that has a design weakness that has been reported for over 100 years!

I won't beat the dead horse any further. Those who want to be convinced will be, and those don't want to be convinced won't. The best advice I can give anyone is do your own tests and see what results you get?

But, think I will be vindicated as I see another report of CBC cases failure reported elsewhere on the internet.

That's three!

I will repeat my recommendations.

Recommendations:

Before shooting any cartridge in a Martini, check the head space of the cartridge to be used. Insert an empty new unfired case in the chamber and make sure it is fully seated. Place a 0.006 inch feeler gauge at the back of the cartridge head and close the breech block. If the gauge is not held by the breech block the rifle should be considered to have failed the NO-GO headspace and it is not recommended to be fired with that case. Repeat the test with a 0.010 inch feeler gauge. If the feeler gauge is not held when the breech block is closed the gun is considered to have failed the FIELD test and should not be fired with that case.

Use solid head cases only.

If you must use balloon head cases use FG powder only. If a brand other than GOEX Fg is used, do test firing and check for head bulging. Head bulging can be checked by placing a straight edge like a steel ruler on the head of the case, and holding the case and ruler up to the light. Tilt the ruler at 45 degrees toward you and look for the light between the head and ruler.


Do not volume load black powder particularly in CBC cases! Weigh all charges and filler on a scale. Do not fill these case to the bottom of the neck with black powder and load.
DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.


richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/10/2005 : 1:40:38 PM
I fail to see the basis for any dispute of what DoubleD has posted. To me, the excellent photos of the cross sections of the brass pretty much says it all. Shotshell balloon head brass has a very thin wall all the way to the very thin head, with a junction that is truly a 90 degree angle without reinforcement. Such a 90 degree angle will focus pressure on the exact apex of the angle, which of course is the joint between case wall and head where my failures occurred. This is a simple matter of physics and isn’t subject to debate. Aside from the solid head having a lot more brass/strength in the head, where the case wall meets the head there is also a taper that provides further reinforcement. Of what I believe is even more important, this junction occurs well away from the base of the cartridge and is therefore well supported by the chamber’s wall. Simply put, reformed shotshell brass is not the functional equivalent of solid head brass. However as I’ve said before, the relative economics between the two gives me a strong incentive to use the shotshell brass as a functional substitute.

The subject of headspace is similarly full of shades of gray. “Safe headspace” is not an absolute number, but a function of action design, chamber design, case design and pressures to be handled. Lacking precise gauges for these rifles, we are left with measuring the space between a chambered round and the breach face. As DoubleD has documented, the rim of a given case design (such as the beveled shotshell rim vs. the straight solid case rim) and a given chamber’s dimensions can result in very different spacing between brass types in a given rifle. Similarly the measured differences between brass types may also be very different in another rifle since a beveled rim will seat further in a slightly larger chamber. Given the wide discrepancy between the various sealed pattern dimensions established over the years and the varying use and abuse of these 100+ year-old rifles, chamber dimensions can be expected to vary quite a bit and therefore the impact of a beveled rim on space to the breach face is a factor in whether a reformed shotshell case can be safely used in a given rifle.

How important is this to the MH rifles being used is a valid question. First, while everyone hand wrings about headspace, in my some 40+ years of collecting involving literally hundreds of rifles, I’ve come across exactly two modern (designed for smokeless cartridge) rifles with serious headspace problems. Both were well worn and of low quality initial manufacture. While relatively new to the world of BP cartridge arms collecting, I must note that of the 7 rifles I own in 577-450, 2 have issues with the reformed shotshell brass. Both of the questionable rifles are of British manufacture apparently still wearing their original barrels with very good+ bores….in other words are not worn out substandard junk. Keeping in mind the bearing surfaces involved in the MH action, I can only conclude that both rifles were probably manufactured with generous headspace, were successfully proofed, and then subsequently issued and used without problems. While my 2 out of 7 is hardly a significant sample from which to form a conclusion, it does give me cause to suspect that the percentage of rifles out there that will have headspace issues with shotshell brass is many times greater than say good condition MILSUP Lee-Enfields or Mausers that will have headspace problems with factory ammo. This posting first warns people of the potential and also gives them hope that a rifle that has problems with the reformed shotshell brass can still be safely used with the more expensive solidhead brass. Considering the relatively expensive nature of our hobby, I think this information provides a service to collectors that otherwise might give up on a rifle that bulges/splits rims on reformed shotshell brass.

While realizing that some people have a significant emotional and/or financial interest in this topic, we should encourage open discussion backed by actual research with documentation provided for all to see. Frankly most of the “facts and conclusions” I’ve read here and on other boards simply lack any documentation, whether from personally conducted trials or from respected published sources, with requests for such resulting in wholly unwarranted personal attacks and ridicule. Not unlike in the fable “The Emperor’s New Clothes,” too many people blindly follow hype and BS and fail to question it despite what they can see with their own eyes….as in the pictures of the casehead cross sections. DoubleD has provided both original research and published sources for his information and conclusions, and has done so without casting aspersions on the IQ of others. Whether we personally like the implications or not is immaterial to the value of the discussion. As I’ve stated repeatedly, I find the low cost of this brass ($.42 a case) very attractive and will continue to use it in all of my rifles that don’t have problems with it. However when I go to gun shows in the future, I’m going to carry a reformed case and a feeler gauge with me in order to determine whether these cases will work BEFORE buying any given firearm. I also will at some point pick up some solid head cases to use in my rifles that need it.

Futher ---- Martini collecting is neither my profession nor my religion, but instead is a primary source of recreation. Lighten up guys, this is supposed to be fun!

Rich in WV…..savoring life one cartridge at a time!

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/10/2005 : 2:56:05 PM

Richard, it appears MCQueenie thinks you have exposed me as a fraud with your statement.

Not at all DD. You are reading too much into my comments.

Care to define what details you are talking about?

Details about the rifle in question...especially early on.

You seem to make it appear that Coyote’s motive in objecting so loudly is business. What motive do you lay on me for wanting to see them fail?

I think its clear Coyote's objections center on the condition of the rifle and his experiences with the cases.

Read the report again. Solid head cases were used through out the tests in the gun that had the head separation and that is in the report. Solid head cases did not separate. That is in the report. Solid head cases had protruding primers a classic sign of excessive headspace supporting the conclusion that the rifle has excessive headspace. That is in the report.

Neither did the CBC cases during your tests. The fact that none of the cases failed proves nothing...doesn't it?

Last word from me on the subject as the animosity level is rising beyond reason. I'm glad you copied and pasted the post from the British Military Forum as that is how I see it.






Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....Edited by - MCQueenie on 05/10/2005 2:58:38 PM

Robert Davidson
Gunboards Super Premium Member


United Kingdom
327 Posts
Posted - 05/10/2005 : 4:10:35 PM
Douglas,
you've done all of us a great service. Thanks very much indeed. We can all make an informed choice, based on what we've read.
In my case, I will pay more money and buy solid cases, since I am at the shallow end of the reloading and engineering skills pool.

richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/10/2005 : 10:42:56 PM
Actually I believe the distortion to the cases makes the case (pun intended) quite well. I know from painful experience that such bulges are a prelude to actual case splits. I also note that the extent of distortion in some of the cases would prevent them from fitting in a shell holder until smartly wacked with a ballpeen hammer to flatten the head....been there done that. Since I experienced the case splits up close and personal, I am of course more motivated than the casual observer as to the factors behind them. I believe two factors distingish DoubleD's trials from my own experience.

First, I was initially using paperpatched bullets. While nominally of the same approximate dimension, paperpatched provides a supior seal with less lubrication compared to a grease groove bullet. I think, but obviously can't prove, that the progressive fouling in the bore provided the additional resistance leading to increased presures and ultimately a increased rate of case failure.

Secondly, DoubleD uniformly firmly seated each round insuring maximum case wall support at the moment of firing, while I just chambered and fired the rounds without the extra step of ensuring the round was seated as far as possible into the chamber. While only a few thousands of an inch difference, as the picture of the cross section shows, it is all it takes to leave the case wall/casehead junction inadequately supported. The ballonhead's unreinforced right angle junction right next to the rim is perhaps the most important distinction between the two types of case construction. This inherent weakness of the design mandates greater attention to headspace than would otherwise be warranted.

If solidhead cases were cheap and plentiful nobody would be reforming shotshell brass as a substitute. However solidhead cases are pricy and if not for the reformed shotshell approach, many people now enjoying the MH would have considered the firearm too expensive to load for. All concerned should recognize the positive contribution these inexpensive reformed shells have made to the spread of the hobby (addiction, obsession, etc), while keeping the inherent limitations of this design in mind.


Rich in WV…..savoring life one cartridge at a time!

DoubleD
Moderator


South Africa
1829 Posts



Posted - 05/11/2005 : 7:34:40 PM
quote: Originally posted by MCQueenie


Neither did the CBC cases during your tests. The fact that none of the cases failed proves nothing...doesn't it?
A very good valid point. I consider a bulged head a failure, but you are right, no heads separated during my test.

I decide needed to more clearly show the the bulged head to show the severity, so I sectioned a case this evening. What a surprise! I should have did this sooner, my apologies.

DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.
Edited by - DoubleD on 05/11/2005 7:38:05 PM

richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/11/2005 : 11:13:44 PM
Since case acquisition and use is at the heart of bringing these antiques back to life and since many of us, particularly newbies, will be using these reformed shotshell cases, may I suggest that the above be edited into a concise summary of issues and findings (while preserving all of the informative graphics) and placed as a sticky at the top of the board. This will preserve the information as opposed to it becoming buried 15 pages back and not readily found even weeks from now.


Rich in WV…..savoring life one cartridge at a time!

DoubleD
Moderator


South Africa
1829 Posts
Posted - 05/11/2005 : 11:56:56 PM
Richard,

What I will do is when the topic goes dormant, I will lock it and stick it to the top of the forum unedited.

I want comments made by those who don't agree with my conclusions to remain as written. I don't want it to appear I showed a bias and edited out remarks that are unfavorable to my report.

I want to show that my work was not accepted by all and that I made an effort to supply answers to questions that were raised.DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/12/2005 : 01:07:45 AM
Thats a very ugly case head there, DD. Very nearly blown off from looking at the cracks in the corners. I'd still like to know where I disagreed with your conclusions...I don't. I simply thought that your reports were focused too much toward the cases themselves and tended to extenuate the condition of the rifle that caused the problem. Maybe a misconception on my part. Again enough from me, already.Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....

richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/12/2005 : 02:17:45 AM
Something about those "cracks at the corner" bothered me. They were just too uniform. So I just now went out to the garage and sectioned a virgin case and low and behold, the beginnings of those “cracks” are already there. Once the case is open, you can run a fine blade (I used a pointed Exacto-knife) around the edge of the now exposed interior of the case and feel the little crevice all the way around. It must be part of the factory case forming process that sizes the base to its final dimensions. It wasn't readily visible at first when I sectioned the case because grains of brass "saw dust" filled the crevice in the process of sectioning it. Rap in on the table a few times, the brass dust falls away showing the crevice. I wouldn't call it a defect, but it is apparently a by product of how the cases are formed that is readily exploited by the pressure focus point at the apex of the angle formed by the case wall/case head junction (this is why dams normally have sloped bases on the water side whether the dam face is sloped or straight). Considering this further thins and focuses stress on the case wall/case head junction, I’m damned impress that these cases hold up as well as they do.

Rich in WV…..savoring life one cartridge at a time!Edited by - richardwv on 05/12/2005 02:27:48 AM

Robert Davidson
Gunboards Super Premium Member


United Kingdom
327 Posts
Posted - 05/12/2005 : 03:16:08 AM
Blimey...that picture of the cross-section of the domed case-head makes me nervous just looking at it.

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/12/2005 : 1:12:38 PM I
'm wandering if maybe the shotgun primered cases might work better? Mine show no signs of buldging like that whatsoever. You have more force acting on the primer itself due to its greater diameter with less surface area for the brass head. Also the larger pocket and different construction may contribute to the overall stiffness of the head. I've not tried the boxer Magtech so I can't compare in my rifle...then again, I may not have a headspace problem to begin with.Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....

DoubleD
Moderator


South Africa
1829 Posts
Posted - 05/13/2005 : 12:37:44 AM
I don't know whether the shot gun primer ones would work any better or not.

If you have any new unfired shotgun primed cases try this. Hold a steel ruler on top of the case and hold it up to the llight and see how flat it is. Load a case and fire it. Check the head again after firing and see if the head bugles. You can check your already fired cases this way also.



DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.


richardwv
MH Forum Moderator


USA
1832 Posts
Posted - 05/13/2005 : 12:44:39 AM
While not a great picture, this is the case I cross sectioned last night. It was one of the ones I crushed the neck on when learning to form these, but that shouldn't have impacted on the base in anyway. Particularly on the left side, you can see the little crevice I was referring to.

Download Attachment: (picture deleted 9/10/2007 due to incompatiblility with new forum software


257.92 KB


Rich in WV…..savoring life one cartridge at a time!

MCQueenie
Gunboards.Com Silver Star Member


USA
843 Posts
Posted - 05/13/2005 : 01:44:37 AM
I already checked all my fired shotgun primed cases DD. Flat as can be.Censorship is the commonest social blasphemy because it is mostly concealed, built into us by indolence, self-interest and cowardice. John Osborne

Joke 'em if they can't take a ....

DoubleD
Moderator


South Africa
1829 Posts
Posted - 05/16/2005 : 11:12:45 AM
I am now going to lock and Sticky this post to the top of the forum. I am also going to change the name to Word of caution about Ballon head cases.

Over the weekend a rumor sprung up that MAGTECH was coming out with a soilid head 577 cases. As of this morning the MAGTECH Public relations would not confirm that. Cross your fingers.

In closing you can safely use balloon head cases in your Martini. Just follow the recommendations below:

Recommendations:

Before shooting any cartridge in a Martini, check the head space of the cartridge to be used. Insert an empty new unfired case in the chamber and make sure it is fully seated. Place a 0.006 inch feeler gauge at the back of the cartridge head and close the breech block. If the gauge is not held by the breech block the rifle should be considered to have failed the NO-GO headspace and it is not recommended to be fired with that case. Repeat the test with a 0.010 inch feeler gauge. If the feeler gauge is not held when the breech block is closed the gun is considered to have failed the FIELD test and should not be fired with that case.

Use solid head cases only.

If you must use balloon head cases use FG powder only. If a brand other than GOEX Fg is used, do test firing and check for head bulging. Head bulging can be checked by placing a straight edge like a steel ruler on the head of the case, and holding the case and ruler up to the light. Tilt the ruler at 45 degrees toward you and look for the light between the head and ruler.


Do not volume load black powder particularly in CBC cases! Weigh all charges and filler on a scale. Do not fill these case to the bottom of the neck with black powder and load.
DD

That isn't your Martini you have. It belonged to others before you and will belong to others after you are gone. Look after it an pass it on with pride. It deserves it....Malcolm Cobb The Martini-Henry Note-Book.
 

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