Maximum chamber pressure for the M1 Carbine?

[Steelman1957]

Hello to everyone, I'm a ST.Louis boy, I'm new to this sight. I'm looking for some info on a M1 carbine. I'm trying to find out the maximum chamber pressure for the M1 Carbine. I want to build a wildcat cartridge with the same spec's as the .357 Mag. (43,000 CUP) MAX. or less. Can anyone out there help me with this info.?

Information

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[ScottR]

40,000 was max, high-pressure test ammo was between 45,000-50,000.

Scott

[Tired Retired]

The design operating max pressure was 40,000 CPU (Copper Pressure Units) which is not the exact thing as PSI. Current SAAMI standards reflect that same amount. However for wildcating, you may want to do a little research. I believe I read somewhere that there was some general (public) experimenting on the .30 carbine platform in the 60's with several safe wildcats produced. It may save you some trouble or help you get some ideas of your safe options.

[CrossedCannons]

The M18 high pressure test cartridge for the M1 carbine produced a chamber pressure of 47500 psi (TM 43-0001-27 - Army Ammunition Data Sheets). I don't think it was proofed from the shoulder.

[Bruce McAskill]

The .30 carbine standard operating pressure is 40,000 PSI. The standard for the .357 Mag. is 35,000 PSI. As to a wildcat cartridge conversion,many have been done over the years and most have failed quite badly. The really successful ones have been base on the .30 carbine case necked down to .22. One man even marketed a .45 magnum version a while ago but it started to destroy the carbine as too much metal was removed from the receivers and needless to say he is no longer in business. The biggest limiting factor to a conversion is the magazine and getting it to feed properly with anything other then the .30 carbine case.

[campperrykid]

FWIW:
Port pressure and gas port size would be another significant issue with any wildcat conversion involving the M1 Carbine platform.

[Bill Ricca]

I don't think it was proofed from the shoulder.

You are correct. All proof firing was done in a separate area to prevent injury if something failed. The below pictures show proof firing of an assembled carbine (left) and a carbine bolt and barrel (right). The firing was done remotely.

[firstflabn]

Nice pic, Bill. Several years ago a History Channel program - perhaps the US episode of the three part 'Guns of WWII' - included film of the proof firing of completed carbines. A gal was squeezing off a quick 15 in the apparatus shown on the left in your photo. Following the proof firing film clip they showed a gang apparatus for cycling slides on assembled carbines. Seems like about seven guns in a circular setup. I will see if I can find the episdoe and the time it appears on the DVD.

[CrossedCannons]

Mr Ricca, thanks for the info, were catastrophic failures during carbine proof testing ever actually documented? And if so, how frequently? Or was the apparatus designed, built and used just as a precaution?

[Bill Ricca]

I am not sure of the procedure shown on the history channel, but proof firing, which is high pressure test cartridges, was not done with multiple rounds, or by hand. I am sure the history channel got the procedures mixed up. One proof round was all that was used, as a firearm could not consistently adhere to the high pressure.

There were devices to test fire with permanent holding due to lack of impact area, like an underground dirt tunnel.

If you notice the text states "safety precautions".

I know of no records of how many firearms failed, but I can tell you talking to an employee at Springfield Armory, it did happen (Garand, M14 and 30 BMG) when they were handling thousands of barrels, bolts and firearms.

Don't know if they kept track of the overall percentage, I doubt it.