un-dentified 9mm ammo

unspellable · 02-06-2003, 02:11 PM

British Proof to 13.5 tons per square inch comes to quite a bit more than 30240 lbf/in^2 cup as the methods of measurement are very different. The cup method formerly used in the US consistently yields much higher pressures than the British Proof method for the same load.

The British Proof method consisted of placing a lightly oiled cartridge in the test chamber and placing a crusher behind the breech piece, essentially measuring the force the rear of the cartridge exerts on the breech face and then calculating it in terms of tons per square inch.

The American CUP method used a copper crusher behind a small piston inserted in a hole in the chamber wall, measuring the force with which the charge would blow a small plug out of the side of the cartridge. Yields larger numbers than the British method for the same load.

Currently in the US we use the PSI method with an electronic transducer more directly measuring the pressure. It reacts mush faster so that a curve is obtained rather than just the total effect on a crusher. This method typically yields even higher numbers han the cup method.

In short 13.5 tons British Proof doesn't sound like so much but it's really one damn hot load! I'd bet good money it would run over 35,000 cup and over 40,000 transducer in a flash and then some. Of course this is the proof load for the STEN, not the working load.

tacfoley, how long is the barrel on your STEN?

02-06-2003, 02:11 PM	#8
unspellable User Join Date: Jun 2002 Location: Iowa Posts: 769 Thanks: 0 Thanked 20 Times in 12 Posts	British Proof to 13.5 tons per square inch comes to quite a bit more than 30240 lbf/in^2 cup as the methods of measurement are very different. The cup method formerly used in the US consistently yields much higher pressures than the British Proof method for the same load. The British Proof method consisted of placing a lightly oiled cartridge in the test chamber and placing a crusher behind the breech piece, essentially measuring the force the rear of the cartridge exerts on the breech face and then calculating it in terms of tons per square inch. The American CUP method used a copper crusher behind a small piston inserted in a hole in the chamber wall, measuring the force with which the charge would blow a small plug out of the side of the cartridge. Yields larger numbers than the British method for the same load. Currently in the US we use the PSI method with an electronic transducer more directly measuring the pressure. It reacts mush faster so that a curve is obtained rather than just the total effect on a crusher. This method typically yields even higher numbers han the cup method. In short 13.5 tons British Proof doesn't sound like so much but it's really one damn hot load! I'd bet good money it would run over 35,000 cup and over 40,000 transducer in a flash and then some. Of course this is the proof load for the STEN, not the working load. tacfoley, how long is the barrel on your STEN?