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Discussion Starter · #1 ·
A while ago I bought some NOS1891 Argentine barrels from Sarco, but they seemed to have threads with an outer diameter that would not hand screw into a receiver at all.

I have a few barrels taken off of 1891 Argentine rifles for comparison.

After seeing mention on a thread a month or two ago, I bought a tap and die set for "Mauser Small Ring". This seems to be a tap and die with the specification of 0.980 inches.

The tap seems to work pretty well in an 1891 Argentine receiver. The original poster who bought the large ring die set said a similar thing. He said that the tap pretty much chases the threads and removes very little metal. He said that the die removed much more metal, but seemed happy with the result.

I opened the die about half way by turning the little set screw and tried it out on an 1891 Argentine take off barrel. I was shocked to measure the outer diameter after this in the 0.97x range. I later turned the tiny screw as far as I dared, but was not able to open the die enough to turn it by hand over the threads on a take off barrel. My father who is a retired machinist said that I should be able to open it enough to basically skim over the threads, then tighten it as necessary.

The die says 0.98 x 12 inches on it and I was told that it was 55 degree Whitworth.

I measured some of my barrels: The take off barrels seem to have an outer thread diameter of 0.950 inches and the NOS barrel 0.988 inches.

I am starting to wonder if the specification of 0.980 inches for a small ring receiver only applies to the receiver and not to the outer diameter of the barrel threads.

Could it be that the barrel threads are intentionally made a little oversize so that they have a tight fit?

I am thinking that the EBAY guy simply had a Chinese factory make a 0.980 die and never actually used them on Mausers. I am starting to think that 0.980 inches is to small to be using as a thread chasing die on these 1891 Argentine Mauser barrels.

I just ordered a 1 inch aluminum tube from McMaster Carr and plan to ask my friend to take it down to 0.985 inches using his lathe so I can practice with the die and determine what the maximum outer diameter it can make is. I suspect that it will not open up much past 0.980 inches.

Any thoughts or experience on this subject will be appreciated.

Thanks.

Joe
 

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Discussion Starter · #4 ·
The eBay guy in Australia had them custom made and said that they would be 55 degree wentworth.

I used my thread gauge against the barrel that I did with the die that came out 0.97x, granted not the best done work, but it seems to match.
 

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I have a book that shows the 91 Argie Mauser has a major diameter of .985, 12 TPI, V thread. The small ring Mauser is .980 major, 12 TPI, V thread. This may help.

.
 

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Discussion Starter · #6 ·
Doug,

Thank you for the information. Please pardon me if I need some clarification. I don't have much experience in the machinist world.

When you say "major diameter" is that the same as what I was calling "barrel thread outer diameter"?

Are you saying that the model 1891 Argentino is not actually a small ring Mauser? Your remark of 0.985 would seem to match my barrel measurements.

What is the name of the book you are referring to?

Assuming that my tap is 0.980 12 tpi 55 whitworth, if I were to use it in an 1891 receiver that is 0.985, am I correct in assuming that it would easily turn and just not go to the full depth and basically just shape the tips of the receiver threads? That is what seems to have happened, with only one or two small flecks of metal being shaved off.

If the 1891 is indeed 0.985, then my die is too small to be useful, right?

I looked at the Hoosier link. It does say that small ring Mausers are 1893 to 1896. When it shows the 1891 Argentino it has no text. Later on in the barrel configuration section it lists the small ring and the 1891 separately, but give 0.980 for both, with a slightly longer thread length (I assume that is what they meant) for the 1891.

Thanks again for helping me.

Joe
 

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Not an expert, but 2 and a half thousandths (per sde) is probably not going to make any difference in the fit or safety of the whole rifle. I would say that the Spanish ones don't have tolerances that close.
 

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Doug,

Thank you for the information. Please pardon me if I need some clarification. I don't have much experience in the machinist world.

When you say "major diameter" is that the same as what I was calling "barrel thread outer diameter"?

Are you saying that the model 1891 Argentino is not actually a small ring Mauser? Your remark of 0.985 would seem to match my barrel measurements.

What is the name of the book you are referring to?

Assuming that my tap is 0.980 12 tpi 55 whitworth, if I were to use it in an 1891 receiver that is 0.985, am I correct in assuming that it would easily turn and just not go to the full depth and basically just shape the tips of the receiver threads? That is what seems to have happened, with only one or two small flecks of metal being shaved off.

If the 1891 is indeed 0.985, then my die is too small to be useful, right?

I looked at the Hoosier link. It does say that small ring Mausers are 1893 to 1896. When it shows the 1891 Argentino it has no text. Later on in the barrel configuration section it lists the small ring and the 1891 separately, but give 0.980 for both, with a slightly longer thread length (I assume that is what they meant) for the 1891.

Thanks again for helping me.

Joe
Yes, "major diameter" is the same as "barrel thread outer diameter". It's the maximum diameter of the threads.

I always thought a "small ring" was a commercial Mauser. But then I'm marries so I'm not supposed to be thinking! The dimensions for the "Small Ring" on the web site I posted match the dimensions I have for the 91 Mauser.

The book is "Bolt Action Rifles" by Frank De Haas. I have the second edition. Here's the third edition, look out they got expensive!

Your 0.980 12 tpi 55 whitworth tap probably wouldn't even clean the threads on the 1891 receiver. Whitworth threads have rounded points on the threads, both on the crest and root, "V" or American Standard are pointy. Even if the tap or die is the right size and pitch, if it's the wrong thread type you can damage the threads.
 

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Discussion Starter · #9 ·
I think I have the first edition of the Hass book. It is very yellow and does not mention edition. I looked through the 1891 section and did not see anything about the thread major diameter, but did see the part in the 1893 section where it said V pitch.

From what I have seen in many other discussions in forums like Practical Machinist and from what I know about early Mauser history, I am pretty sure that they were sourcing their equipment from England and following the English Whitworth thread profile. I think that Haas may be mistaken. I noticed another mistake saying that the 1892 Spanish (Navy) Carbine was 7.65 mm, when it was actually 7 mm, so it would not be impossible that he was wrong about the V pitch.

I measured the major diameter on two take off 1893/33 Turkish Mauser barrels and it is very close to 0.980. So I think what you are saying about the 0.985 major diameter for the 1891 makes sense.

In any case, I will hold off on using the die on any more barrels. I will try it on my aluminum tube. I also have a Whitworth thread repair file. I had been using that to work on the NOS barrel threads that were more like 0.988. I would chuck the barrel in my friend's lathe and push on it for an hour with the file. I finished one barrel and was able to install it in a NOS receiver.

Unfortunately, my friend is in the process of selling his business and it will be a stretch to be able to continue to use the lathe.

Thanks again for the help.

Joe
 

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I suggest Haas describes a thread as either "V or Square".....without reference to the actual dimensions......if you look at Mauser design drawings ,the thread form is defined in minute detail......I would also suggest using taps and dies to fit a barrel is a shortcut to drainpipe fit threads.......maybe a bit of white lead and oakum to take up the slack.
 

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First, there is an unfortunate practice that many in the US use to define Mauser's as Small Ring, or Large Ring. The causes problems as there is such a variance. Additionally you are not asking about Small Rings, you are asking about Small Threads. It gets further confusing when you have Large Rings with Small Threads, and Small Rings with Large Threads.

The original spec for all of the "small thread" mauser's was a 25mm major diameter. That is approximately .984. This includes the Spanish 1893, the Chilean 1895, and Turkish 1903. I do not have any primary documents related to the 1891's, nor the Swedish 1896, nor the Mexican 1902's. The length of the threaded shank DID VARY.

It is common practice to make the major diameter a CLEARANCE so that there is no risk of interference. The pitch diameter is what locates the thread.

Plus or Minus .003" is a common tolerance TODAY.

I measured a few small thread barrels and the major diameters varied over .01" and the pitch diameter's varied over .015".
 

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I just bought two screws and a die for the front guard screw on a No.4 MKII action. These are 55 degree whitworth threads. Take the barrel and check out motorcycle shops that cater to foreign MC brands.If you find a knowledgeable shop they may thread the barrel shank for you. And all you are doing is chasing the threads. I bought my taps and die from a bicycle shop in New York State. Hope this works out for you. Frank
 

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Discussion Starter · #13 ·
Update on my die situation.

I bought a one inch aluminum tube and had my friend narrow it to 0.980 on one end and 0.985 on the other. I opened the die as far as it would go and practiced on the tube. On the wider end it made nice threads with a major diameter of 0.982.

I tried it on one NOS barrel that I had partially reduced using a thread repair file. It took off a little metal and adjusted the thread profile. I was able to screw it onto a receiver and had very nice headspace.

I tried the die on another NOS barrel that I had reduced enough with the tread file that I could be screwed into a receiver, but with headspace of GO + 0.007, which is Field gauge range. I took it off and ran the die on it. The die took very little off, basically chasing the threads, but the headspace was GO + 0.004 after screwing it back on.
 

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Stacking tolerances. I have a nice VZ 24 action and four 98 mauser threaded barrels. The 8mm Persian Carbine barrel won't screw on but one or two threads. Next one is an Argentine Mauser 98 action threads and that is the same as the first. Third is a 7mm mauser barrel and has 98 threads. That one also will not screw but a couple threads. But the kicker is the Norwegian 7.62x51 Nato barrel. That one will screw by hand all the way. One action and four different barrels in 4 cartridges, made by 4 different mfgr's. Frank
 
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