Please identify fake or not


Good evening Gentlemen.
This cartridge has been floating around in my collection for a while and I am still trying to identify it. The bullet is 7.38mm (.291") with case length 55mm. Lead bullet. The headstamp looks American, much like the WW1 303 British, however the dimensions are different.


Hi Daan, nice round! It is an autofrettage cartridge for Mosin-Nagant rifle barrels made by New England Westinghouse Company.


Thanks Fede for the reply. When I got the round it was in a mixed bag of Nagant cartridges, so I should have started searching there. Is there some material on the autofrettage research?


Daan, the autofrettage is a metal fabrication technique used for strengthening cannon barrels. I’m sure you will find a lot of detailed information on the web.


I have one exactly like that but yours is nicer. I’ve never really been able to find much info on them. Neat cartridge!


Auto-frettage involves a controlled stretching of the barrel steel so it is only done to an unfinished barrel which can be finish bored after auto-frettage. The old built-up big guns had steel hoops which were made undersized, heated up to expand, and then put over the outside of the barrel and allowed to cool and thereby shrink to a very tight fit. This put the barrel into a state of compression which stiffened and strengthened it. By this method lighter barrels could be made which were as strong as the monolithic “fat” ones. Later it was found that applying a very high pressure to the inside of a barrel slightly stretched the inner layers and left the outer layers within their elastic limit, similar, to the hot hoop method.

The controlled auto-frettage pressure could be applied by a special cartridge or hydraulically. Bofors 40/60 barrels were hydraulically auto-frettaged.



I believe that in U.S. small arms manufacture circa 1850-1920s it was accepted practice to proof test the barrels in a rough bored condition, prior to rifling and finish turning to outside dimensions. These used very heavy bullets to generate the desired pressures with the intent to burst any barrels with flaws before wasting time and effort finishing them. During the period when barrels were made by foldng iron or steel around a mandrel and hammer welding the longitudinal seam this was probably a cost effective test. Later methods of making barrels from drilled blanks instead of welding around a mandrel probably resulted in eliminating the practice which likely revealed relatively few flaws compared to the cost and trouble of doing the initial “burst” proof test, and only a final proof test of the finished barrel/arm was conducted.

While “auto-frettage” is certainly an accepted practice with artillery as outlined in the posts above, is it possible that the cartridge shown is actually intended for use in a “burst test” function, and not as a form of “auto-frettage?”

The U.S. Ordnance Department was notoriously slow to change processes, and the Russian inspectors in the U.S. during WW1 were obsessively picky about minor details, so this cartridge and its associated use may have been required “because we always did it that way” rather than for “auto-frettage” benefits.

Who has examples of the “burst test” cartridges used with U.S. arms manufacture for comparison?


The US military degination for these kind of cartridges was “barrel proof” and several case configurations and loadings were made for Model 1898, 1901 and 1903 rifles. Here is an example from the Pitman notes:


Due to the mathematics of hoop stress, auto frettage makes sense for larger-diameter barrels to minimize wall thickness needed, but not so much for small diameter bores. I note the cartridges shown do not have flanges or extractor grooves. Am I correct in assuming that the unfinished barrels were pressure tested in a special breech fixture that did not provide for extraction, and also that their lack of an extraction surface made the cartridges less likely to be confused with standard rounds?

For those interested in stress calculations involving cylindrical pressure vessels, Google on the topic of Barlow, Boardman, and Lame formulas.


These cartridges were fired in unfinished barrels with chambers “in proof stage” whose dimensions match those of the proof cartridge. As an example, this is a Model 1903 rifle chamber in proof stage as made by 1916:


Great information. Has anyone ever seen anything actually showing this done by Westinghouse to Mosin Nagants? It’s interesting to me that I’ve a few of these same headstamps but never anything from Remington or the Russians. Here is mine by the way, same headstamp as above.


Westinghouse contracted out some of it’s work to other makers, I guess it could make sense that one of them used this method of proofing barrels before assembly and others didn’t. That would explain why these are sort of scarce and why I haven’t seen or heard of any other types. I have certainly seen way more Remington and WRA 7.62x54R proof rounds than these.


Does anyone know what the parent cartridge case for this barrel proof cartridge was? The headstamp suggests perhaps the .303 rather than the 7.62 m/m Russian. What is the diameter of the case at its base? Jack



I don’t believe there was a “parent” case for the barrel proof cartridges. They were manufactured specifically for that purpose. At least that was how the two U.S. cartridges were made (for the Cal .30 Krag & M1906).

For me, a bigger question is what is the reasoning behind the very similar looking 284 Winchester proof cartridge. It has been discussed here, more than once, and I don’t think anyone has come up with an answer.



Ray, I don’t have an answer for you, but will ask another question that may represent the reason for the lack of the time. Where there any .284 rifles where a cartridge had to be feed from the magazine rather than placed directly into the barrel because the extractor would not snap over a rim when closing the bolt, as opposed to the cartridge being feed up under the extractor from the magazine and then pushed into the chamber? If so, these may have been to ease loading one into the chamber for proofing of such rifles, without have to magazine feed the rounds. Just a though - actually just a WA guess.


The base of mine is .460, and you can see where the rim has been turned down.


A .303 British of the same headstamp as this auto frettage has a base of .458 just in front of the rim (if you don’t measure at the rim-undercut), and as hendere notes his is AF .460, mine is .463 over the rim-turned-down area. The case length of mine AF is 2.162" and the .303 case length is 2.224.

So it would seem to me that a U.S.C.Co…303 British was the parent case. It was an unfinished case without the rim-undercut, a turned off rim, a lower placed shoulder and a mouth trim.


Hendere and Pete: Thanks for the information and thoughts. The idea this was based on USC-produced .303 brass seems reasonable. Jack