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Confusion over Mk VII Sealant partially solved

3K views 50 replies 17 participants last post by  GunnerSam 
#1 ·
The sealant used in the Mk VII cartridge is variously described as "Beeswax" or an "Asphaltum".
The confusion is apparently due to the fact that sealants of this sort are almost always combinations of several constitutients.

The Treatise on Ammunition Page says this about the Mk VII cartridge.
"A cannelure is formed around the base and this is filled with Beeswax"

The Mk VI is also described as using a Beeswax lubricant/sealant.

Further on the illustration of .45 cartridge for the Nordenfelt gun shows a thick Beeswax Disc placed over the waxed card wad.

It is common for Bitumenous sealants and paints to contain Resins added to increase resistence to heat. The most heat resistent of these seems to be CNSL derived from Cashew Nut Shells which contains a formaldehyde resin.

Resin and Beeswax mixtures used since the time of the Ancient Egyptians are commonly mis-identifed as Asphaltum, which they closely resemble.

Now if one of the resident experts on the sealants used by the British Military would take the time to look up the exact composition of the sealant as aproved at various stages of development of the cartridge we can figure out just why the sealants are described both as Beeswax and as asphaltum. We can also find out which resins we are dealing with in cleaning bores.
 
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#37 · (Edited)
With copper, gilding metal and brass, the commonest reason for brittleness would be work-hardening and insufficient annealing. Cupro-nickel, however, has a tendency to become brittle from annealing at temperatures only a little excessive. Since an arsenal skimping on annealing is more likely to have it show up in the cartridge case, I think overheating is more likely than not doing it.
Good information there, at last we are getting somewhere.

Bullet cores are usually lubricated for the swaging process, and it has to be a lubricant with a very high flash-point, due to the pressures involved in the process. Modern swagers use lanolin, a byproduct of the wool industry, which didn't exist in India. So in wartime they might have used anything, and it might have caused that smell.
The compressed paper nose filler would soak up residual lubricant. I remember thining at the time that the filler might be impregnated with a resin binder but the paper can out in tiny strips and shreds with nothing holding it together.
The British had exactly the excuse the Americans have to use the current or previous M16 bullets, no more and no less. It was alarming, but not seen as being against the laws they had signed up to. This is debatable, as the definitive text in the agreement was the French one, in which "s'epanouissent" has more of a suggestion of any kind of spreading out, rather than just expansion. That might perhaps more reasonably have been interpreted to include breaking up, but almost everyone has chosen to interpret it differently.
I never liked the idea of the early M16 bullets breaking up like that. The rifle wasn't intended for a long range role where the effect would be less terrible.
Probably wounds at longer ranges using the aluminum nosed bullet wouldn't have been as terrible.

Range makes a great deal of difference in penetration even when using AP.
At extreme close ranges the longer bullet is still yawing, it takes at least 50 yards to begin to stabilize. An AP bullet generally penetrates better at 200 yards than at ranges under 10 yards for this reason.

Similarly there is a letter of Churchill's on record, to the Minister of Food I think, deploring the lack of an extra sugar ration to beekeepers, since British bees require an allowance of sugar syrup to get them through the winter after most of their honey has been taken. I don't know if the bees thereupon received special consideration, but it seems likely that beeswax supplies might have been restricted in wartime, resulting in a search for other substances to mix with it.
I figure that by WW2 they'd already decided that the excessive deposits of resins at the throat and chamber neck were making it too difficult to get the bore really clean and chose to go to a neck sealant that left less deposits. The resins added to Cordite MD were doing a better job and burning away with each shot.
Some later propellant formulas reduced erosion further but were no ready to completely replace the propellants already in use and in storage. So some ammo used the black sealant and some didn't.

I had guessed that something quite different from the glass, which alone was mentioned, broke up the bullet. I knew someone who took grave harm from an olive once. A large number of martinis without did him no harm whatever, but it was the one with the olive that did for him.
Yeah you'd have to go through the outer sheet metal to get to the glass.
There are stamped reinforcements of even heavy and tougher steel but the bullet had not hit those.
When a bullet encounters successive layers of greatly different materials the effects are not easy to predict.

70's US Sedans are built like tanks compared to modern cars and most european cars.
Back in the early 90's some Kuwaitis came through here buying up a specific model of Chevolet to replace those Saddam's troops had stolen. Seems like it was the favorite of body guards over there. They'd asked about these at my Nieghbor's body shop offering top dollar and arranging complete overhauls and such, putting them back in showroom new condition.
I guess they were more familar with the design and had plenty of spares for that model still in stock. Probably it was a good body to armor up.

Found this book except that if correct would give an idea the sort of black market POF ammo still floating around.
Some of the POF stamped ammo may be counterfiet or assembled on scrapped cases.
http://books.google.com/books?id=M_...hl=en&sa=X&oi=book_result&resnum=10&ct=result
 
#39 ·
Cordite MD consists of Nitroglycerine, guncotton, and mineral jelly...period. Solventless Cordite (cordite SC), formulated after the war when RDB had proven unstable, had Carbamite added as a stabilizer...as it is still used in NC propellants for the same purpose today. The only resin added to Cordite that I've been able to find mention of. As a side note, they apparently didn't find the black stuff (whatever it is) too objectionable during WWII, as I've got '45 dated Royal Labs stuff with it around the case neck. I'll check the '50s dated Brit ammo I have when I get a chance.

The triple base cordite N and it's relatives, had nitroguanidine (sp?) added as the third base, which produces nitrogen when heated, both cooling the burn and reducing the flash...only used in naval guns as near as I can tell. They tried adding mineral jelly to the nitroguanidine to act as a lubricating barrel coating, but had no luck as it vaporized entirely upon firing...it did, however, act as an erosion moderator by the same mechanism used on cordite from the beginning...it modified the burn, making it less efficient (cooler).
 
#40 ·
Cordite MD consists of Nitroglycerine, guncotton, and mineral jelly...period.
I'll get back to this as soon as I've finished checking the types of Hydrocarbons in Vaseline and whether any of these is a Hydrocarbon Resin.
Moderation of the temperatures and slowing the expansion of gases may have had the effect of leaving a hydrocarbon resin residue that would have had the effect noted in the alternating axite and cordite experiment.

I'd been thinking of this as a matter of additives but it may be a matter of natural contaminants. Few products are anywhere near chemically pure and mineral Jelly is a mixture of many hydrocarbons. Never heard of any 100% efficiency in any explosive or propellant even theoretically.
I just don't believe any explosive or propellant can leave no residue.

PS
I finally figured out how beets are connected to Russian Tallow. Russian Tallow had some superior qualities attributed to the fodder the Russians used for their cattle , dried vetgetables, and "Fodder Beets" was the main difference.
Could be the Beets had an effect on the fat at a molecular level.

I'd like to find out the exact formula used for the Cordite in late manufacture Dominion ammunition, down to the last detail.

The lanolin sealant/lube is something else I need to look into. Lanolin is a cleansing agent, but how it reacts at high temperatures I've never heard.
Odd but Alchemists called Lanolin "Baby Boy Fat" in their coded notebooks, which got a few of them in a lot of trouble if any children disappeared nearby when they were running their experiments.
 
#41 · (Edited)
I'm in agreement that only petroleum jelly was added to cordite, at least until the late twenties, when that is what the "Textbook of Small Arms" says. While asphalt is a mineral oil product, any as an unintended impurity in petroleum jelly must have been minute, and the proportion of mineral jelly in cordite was small. So the chance of its being deposited in a layer from burning cordite seems non-existent, and the chances of that shifting gas erosion to a down-bore position seems not just 2x non-existent, but non-existent².

The largest naval guns are remarkably similar to rifles in velocity, pressure, and barrel length when expressed in calibres. But they differ extremely in two respects. Bore time is very much longer, and erosion a much more severe problem, with bore life being as little as 200 rounds, or down to about 70 in specialised cases such as the German Paris Gun. To some extent erosion is a result of bore time, but I think there is another cause. A flame looks opaque to the eye, but is transparent to radiated heat, and being incandescent, it does radiate very strongly. For a given inch of barrel, the area of surface receiving the heat is proportional to the bore diameter (π times diameter, to be precise). But the heat being radiated is proportional to the cube of bore diameter, a much greater figure. The large artillery bore gets hotter on the surface, and not being fired as often as a rifle, may also be cooled more quickly by the cold metal beyond.

So erosion protection by any means, even means otherwise counterproductive, assumes much greater importance in very large artillery.

We have seen a change from glazed card to strawboard disc wads over the powder, because of use in synchronised aircraft machine-guns. This was a feature of the pre-war years, in British service, as it meant guns firing between the blades of the airscrew, and as the "Textbook of Small Arms" of 1929 mentions only glazed board, I think the other came in the early 1930s. I believe the glazed cards must have spun off in a less predictable direction than the bullet, and scarred the airscrew, which may still have been wooden at the time. More brittle strawboard would have broken up. It does suggest that there was good reason not just to omit the thing altogether, and although I can find no authoritative explanation, I think it was most likely to avoid melting of the exposed core. This could only have been superficial, and is unlikely to have materially impaired accuracy, but deposition of lead may have interfered with the functioning of automatic weapons.

I referred to lanolin and perhaps its substitutes only as a lubricant inside the bullet, from which all external traces would have been removed before loading. It was probably an emulsion with water, inhibiting flashing, although such a thing as anhydrous lanolin exists, and is a constituent of a bullet lubricant recently adopted by cast bullet shooters. But I have never heard of, and I doubt, its use on the outside of a bullet in earlier times. Incidentally its use in shampoos etc. isn't as a cleaning agent, but to prevent excessive degreasing of the hair.

What I have used satisfactorily for jacketed bullet swaging is STP gasoline additive, a peculiarly sticky and non-volatile hydrocarbon which more shooters must know as case sizing lube. It costs a fraction the price of little plastic tubes from the reloading equipment makers.

Even the Textbook refers to beeswax in the cannelure as a lubricant, but there is room for very much less of it than would suffice for cast bullets. It can be argued that lead alloys need it more. But the way insufficiently large or insufficiently filled lube grooves work, is that the lube is exhausted by the time the bullet reaches the area near the muzzle, where it needs it most. None left is none left, whatever your bullet is made of - and besides, no lubricant is what nitrocellulose MkVII .303 got for many years, being sealed with a cellulose and solvent lacquer.

The air seems to have cleared around here, and long may it continue, one way or another. If the internet is anything like conversation, it is conversation in a crowded street, where anyone can listen, and anyone, with any standard of behaviour or level of interest can join in - and either be answered or have his opinions taken as true. As in many areas of science, the casual thinker can sometimes come up with an explanation or snippet of information which benefits us all. But it isn't always like that.

I wouldn't attribute too much to political change in the US, for I can't see much changing online in the next year or two. But there is no doubt that the commercial necessity, on the American gun market, to provide a home for racism, chauvinism and abusive argument, has seriously befouled our use of the internet. It is an unnatural outlet for the person forced to restrain himself in everyday life, and there are boards where there seems to be an extra rule that you don't have to obey the stated rules. Just take a look at the Sound Off and Right to Keep and Bear Arms board, to see how civilisation as we know it could end, let alone the boards they can't let even ordinarily registered members see. (I'm sure the anti-gun campaigners do, whenever their energy flags, and come away fortified.) No wonder that rubs off here. At the moment this street leads from the wrong part of town.
 
#46 ·
I'm in agreement that only petroleum jelly was added to cordite, at least until the late twenties, when that is what the "Textbook of Small Arms" says. While asphalt is a mineral oil product, any as an unintended impurity in petroleum jelly must have been minute, and the proportion of mineral jelly in cordite was small. So the chance of its being deposited in a layer from burning cordite seems non-existent, and the chances of that shifting gas erosion to a down-bore position seems not just 2x non-existent, but non-existent².
Yet the RAF MGs jammed due to fouling in less than 300 rounds and the gun required redesign to avoid excessive fouling.

The largest naval guns are remarkably similar to rifles in velocity, pressure, and barrel length when expressed in calibres.
Theres a great deal more available information on research done on propellants for these guns.

But they differ extremely in two respects. Bore time is very much longer, and erosion a much more severe problem, with bore life being as little as 200 rounds, or down to about 70 in specialised cases such as the German Paris Gun. To some extent erosion is a result of bore time, but I think there is another cause. A flame looks opaque to the eye, but is transparent to radiated heat, and being incandescent, it does radiate very strongly. For a given inch of barrel, the area of surface receiving the heat is proportional to the bore diameter (π times diameter, to be precise). But the heat being radiated is proportional to the cube of bore diameter, a much greater figure. The large artillery bore gets hotter on the surface, and not being fired as often as a rifle, may also be cooled more quickly by the cold metal beyond.

So erosion protection by any means, even means otherwise counterproductive, assumes much greater importance in very large artillery.
The No.1 barrel is relativelt slim and light compared to many infantry rifles, mass of barrel steel acts as a heat sink.
The handguard protect the hands but they prevent the barrel from cooling as quickly.
MG barrels are much heavier and water cooling works to reduce thermal erosion. A heavy watercooled MG barrel can last for more rounds than a light profile rifle barrel if the MG is fired in bursts.

We have seen a change from glazed card to strawboard disc wads over the powder, because of use in synchronised aircraft machine-guns. This was a feature of the pre-war years, in British service, as it meant guns firing between the blades of the airscrew, and as the "Textbook of Small Arms" of 1929 mentions only glazed board, I think the other came in the early 1930s. I believe the glazed cards must have spun off in a less predictable direction than the bullet, and scarred the airscrew, which may still have been wooden at the time. More brittle strawboard would have broken up. It does suggest that there was good reason not just to omit the thing altogether, and although I can find no authoritative explanation, I think it was most likely to avoid melting of the exposed core. This could only have been superficial, and is unlikely to have materially impaired accuracy, but deposition of lead may have interfered with the functioning of automatic weapons.

I referred to lanolin and perhaps its substitutes only as a lubricant inside the bullet, from which all external traces would have been removed before loading. It was probably an emulsion with water, inhibiting flashing, although such a thing as anhydrous lanolin exists, and is a constituent of a bullet lubricant recently adopted by cast bullet shooters. But I have never heard of, and I doubt, its use on the outside of a bullet in earlier times. Incidentally its use in shampoos etc. isn't as a cleaning agent, but to prevent excessive degreasing of the hair.
Lanolin is a major cleansing agent, it may have other uses but it disolves grease and oil, garage mechanics have used it daily for as long as the properties were known.
Its properties may make it easier on hair because its a natural substance found in a sheep's fleece.
Its not a harsh detergent.
The Lanolin was mentioned as a ingrediant of a sealer/lube in an earlier post.

What I have used satisfactorily for jacketed bullet swaging is STP gasoline additive, a peculiarly sticky and non-volatile hydrocarbon which more shooters must know as case sizing lube. It costs a fraction the price of little plastic tubes from the reloading equipment makers.
Good clue "non volatile hydrocarbon", I can use that in my search.
Even the Textbook refers to beeswax in the cannelure as a lubricant, but there is room for very much less of it than would suffice for cast bullets. It can be argued that lead alloys need it more. But the way insufficiently large or insufficiently filled lube grooves work, is that the lube is exhausted by the time the bullet reaches the area near the muzzle, where it needs it most. None left is none left, whatever your bullet is made of - and besides, no lubricant is what nitrocellulose MkVII .303 got for many years, being sealed with a cellulose and solvent lacquer.
Heat shielding properties of compounds were often discovered as "by guess and by golly".
 
#42 ·
GunnerSam,

You've constructed a series of theories based on your view that cordite is much hotter and more damaging than contemporary NC powders.

Can you quantify this? How much hotter is cordite than NC - is it 10%, 20%, 60%, 200%? I.e. what difference would be significant enough to cause accelerated erosion?

p.s. you've cut and pasted another lump of hearsay in one of the ammunition stickies. I'm not replying there, because the stickies are intended for facts - pictures, surveys, polls, etc. The PPU MkVIIIz you referred to is well known - I've fired more than 1,000 rounds of it myself. In fact the stuff had near identical ballistics to MkVII/z at all ranges, and it chrono'd in exactly the same zone as MkVII. The bullet was around 175 gn, and the only significant difference being that it had a boat-tail bullet. I.e. it was true MkVIIIz - simply MkVII/z with a different bullet, and no hot/heavy/rifle-stretching peculiarities. I would guess that the identical same round is what Privi Partizan is now retailing as "MkVIIz".
 
#44 ·
GunnerSam,

You've constructed a series of theories based on your view that cordite is much hotter and more damaging than contemporary NC powders.
Excuse me but the "view" that cordite is hotter and more damaging than NC powders is not a personal theory. I can't think of any authority on the subject who'd claim otherwise.

Can you quantify this? How much hotter is cordite than NC - is it 10%, 20%, 60%, 200%? I.e. what difference would be significant enough to cause accelerated erosion?
To give you an idea the drop in operating temperature between Mk 1 and MD greatly increased barrel life, yet Cordite MD was still much hotter than any NC propelent that remained in use.
I posted thermal properties of Cordite VS contemporary single based NC powders either in this thread or the earlier one.
Theres never been a doubt cordite has worn out barrels in fewer rounds than quality NC powders in loadings of the same power levels.
The only doubts are in the observed wear patterns of bores, and factors that produced the variations in wear patterns according to specifics of ammunition and weaponry involved and methods of reducing erosion.
Its not just Cordite that had these thermal properties the early Double Based powders also eroded bores quickly , some worse than cordite,and were abandoned for anything except special purposes.

p.s. you've cut and pasted another lump of hearsay in one of the ammunition stickies. I'm not replying there, because the stickies are intended for facts - pictures, surveys, polls, etc. The PPU MkVIIIz you referred to is well known - I've fired more than 1,000 rounds of it myself. In fact the stuff had near identical ballistics to MkVII/z at all ranges, and it chrono'd in exactly the same zone as MkVII. The bullet was around 175 gn, and the only significant difference being that it had a boat-tail bullet. I.e. it was true MkVIIIz - simply MkVII/z with a different bullet, and no hot/heavy/rifle-stretching peculiarities. I would guess that the identical same round is what Privi Partizan is now retailing as "MkVIIz".
The warning notice on the blown out extractor was something I ran across while looking into bolt head failures due to excessive pressures. Would you rather no one looked at such warnings?
It doesn't occur to you that there might be variants in manufacture or that some lots of ammunition might pose a danger?
That warning said the ammunition worked okay in a No.4 in good condition but blew out the extractor of a worn no.4.
Should prospective users who might consider using this ammunition in a No.4 with significant wear not be advised of a possible hazard?
It also suggested that the round not be used in the No.1 rifles because it can stretch the action body.
The action body of the No.1 flexs a tiny bit with even relatively mild Cordite loads otherwise there would not be an offset to the front sightbase to compensate for altered haromics.
Why overstress an action when its un necessary?
Metal fatigue effects every metal object sooner or later, no firearm is immune to the effects of time.


No I'll get back to this later.
Things to consider.
Though the majority of fouling from use of ammunition loaded with Cordite comes from the sealant the presence of harden black fouling in the end cap of aircraft guns which drasticaly effected performance shows that something else was present.
The need to alter the parent design and prototypes of the brengun to move the gas port back 9 1/2 inches was attributed to "cordite fouling".
The position of the Bren Gun gasport corresponds roughly to the hotspots I mentioned earlier. The positioning of the port suggests that this spot was chosen because there was less fouling from the propellant left there.

PS
Why would anyone choose a username that is used as slang for the Toliet or the Female private parts?
 
#43 ·
Vaseline was added to the nitroguanidine component of the triple base cordites in an attempt to provide a lubricative coating in experiments at RNPF Caerwent...it failed in that regard as the vaseline instantly vaporized, although it was successful as a temperature moderator.

A reference to these experiments in a paper on the history of the propellant factory at Caerwent can be found here: http://www.caerwentcom.com/rnpf01.htm
 
#45 ·
The warning notice on the blown out extractor was something I ran across while looking into bolt head failures due to excessive pressures. Would you rather no one looked at such warnings?
It doesn't occur to you that there might be variants in manufacture or that some lots of ammunition might pose a danger?
That warning said the ammunition worked okay in a No.4 in good condition but blew out the extractor of a worn no.4.
Should prospective users who might consider using this ammunition in a No.4 with significant wear not be advised of a possible hazard?
It also suggested that the round not be used in the No.1 rifles because it can stretch the action body.
The action body of the No.1 flexs a tiny bit with even relatively mild Cordite loads otherwise there would not be an offset to the front sightbase to compensate for altered haromics.
Why overstress an action when its un necessary?
Metal fatigue effects every metal object sooner or later, no firearm is immune to the effects of time.
Exactly the heart of the matter. It would be of much greater service to have real and conclusive documentation of this incident and it's cause(s). Was the ammo modified (as in clipped tips, for example)? Was it in actuality a squib? And so on...

Purely as illustration, I would cite the exploding cadet rifles, the investigation conclusively proved human error in both cases, yet the rumor mill made for some lurid reading.

Of course safety always needs to be served...it is best served by accurate information.
 
#47 ·
Exactly the heart of the matter. It would be of much greater service to have real and conclusive documentation of this incident and it's cause(s). Was the ammo modified (as in clipped tips, for example)? Was it in actuality a squib? And so on...
Show me a researched and documented credible claim that either the No.1 or No. 4 Bolthead cannot fracture due to excessive pressure.
The Enfield rifles have some sterling qualities but they are not immune to the laws of physics.

Purely as illustration, I would cite the exploding cadet rifles, the investigation conclusively proved human error in both cases, yet the rumor mill made for some lurid reading.
Show me the reports on the "investigation". All I've seen is a single quote from a single source who mentions two incidents which may have nothing to do with the incidents which resulted in the recall of the No.4 rifles.
Of course safety always needs to be served...it is best served by accurate information.
Better safe than sorry, and best that if any error be made it be made on the side of caution.

Thats it for now, I have some research to do.
 
#48 ·
“PS
Why would anyone choose a username that is used as slang for the Toliet or the Female private parts?”


The two key words here are British humor NOT insults GunnerSam, but why would someone call himself "Thunderflash" in another forum?
(Are you trolling for answers or just hungry for humble pie again?)


"Thunderbox is a rock studio album by English rock group Humble Pie released in 1974. It reached #52 on the Billboard 200 album chart in the United States. Incidentally, the word Thunderbox is a seventeenth century slang word for the toilet which gives an example of Humble Pie's sense of humour."
 
#50 ·
Show me the reports on the "investigation". All I've seen is a single quote from a single source who mentions two incidents which may have nothing to do with the incidents which resulted in the recall of the No.4 rifles.
Take it up with Cpt. Laidler, he no doubt could show you that very report. Personally, I'm willing to take his word for it.
 
#51 ·
from the post by Laidler which is always quoted
As for the crazing problems, well, while there was crazing, and I saw some, we used a bore-scope and if 'in the opinion of the examining armourer' it was excessive, the rifle was scrapped. But I never saw a service rifle that exploded because of it! We did have a very good example of it for illustration purposes and a few cut-away barrels at Shrivenham.
Of the two rifles that hit the headlines, the spectacular one
There have been incidents since then involving Cadets acting like dummies or not knowing about safety issues, I found a few news stories on those but no public outcry.

As I mentioned earlier Laidler's remarks have been taken out of context in order to give the impression that Craze Cracking is a myth or that Craze Cracking can not produce an unsafe condition.
Also Laidler mentions the use of a bore scope, which I also suggested, because this sort of damage may not be visible by looking from one end or the other.

Now I have things to do.
I'll get back to this latter.
Laidler mentioned the sectioned barrels, I've seen photos of sectioned barrels illustrating the sort of localised gas erosion I mentioned, perhaps I can find a photo.
PS
The form of damage caused by thermal Gas erosion is not uniform, In most cases it wears away, but in others it leaves raised crater edges. In some areas the bore is smoothly washed away and in others little is removed but the suface is cratered, not pitted in the same was corrosion pitts steel but from high energy impact by particulates and high temperature bubbles which form from an effect similar to Cavitation in high pressure fluids. The super heated particulates and heat bubbles strike the steel like tiny meterors. The damage is microscopic at first but the effects become visible , craze cracking would not even become visible to the bore scope if not for the effects of gas erosion or chemical erossion and corrosion.

I'll get back to this when I find an online source which explains thermal/ gas erosion better than I can.
 
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