Pressure

222remmag · May 11, 2002, 07:48 AM

Does anyone know what the famous 32,000CUP safe pressure limit for a Ruger 45 Colt would be when measured in psi?

Art Eatman · May 11, 2002, 09:46 AM

I've read conflicting comments about comparisons. I've read that there is no direct correlation; I've also read that CUP's are less than psis.

Absolutely nothing more than a guess, but 32,000 CUP might be around 35,000 psi.

I vaguely remember when the factories first started publishing CUP instead of psi. Rifles which had been quoted at 53,000 or 55,000 psi were then being quoted at some 49,000 to 50,000 CUP. Roughly.

FWIW, Art

222remmag · May 11, 2002, 12:05 PM

I seem to remember reading that rifle loads w/SAAMI max's of 50,000-52,000cup measure 60,000+psi w/piezo electric transducer. I have never seen a comparision for lower pressure handgun loads and am hoping someone here has more info.

Chemistry · May 12, 2002, 12:30 AM

Unfortunately, there really is no direct way of converting copper crush units to psi.

222remmag · May 13, 2002, 03:11 PM

In general, I am asking if anyone has seen any data on tests of the same loads by the two different pressure measuring methods. I know that you can't convert one to the other.

bfoster · May 14, 2002, 07:29 AM

I've got both forms of test equipment, an old crusher gun and a Oehler system. Despite the common notion that psi values are always higher than crusher values for a given load this isn't always so, particularily with handgun ammunition.

From the limited amount of work I've done with this cartridge, my notes indicate that with lead bullets in the 250 grain range, and slow burning powders (H110 & IMR 4227) a 32,000 CUP load will roughly be the equivalent of a 30,500 psi load.

Bob

222remmag · May 14, 2002, 11:36 AM

Very interesting, Bob. Have you seen any published data?

May 11, 2002, 07:48 AM	#1
222remmag Junior Member Join Date: May 11, 2002 Location: NH Posts: 5	Pressure Does anyone know what the famous 32,000CUP safe pressure limit for a Ruger 45 Colt would be when measured in psi?

May 11, 2002, 12:05 PM	#3
222remmag Junior Member Join Date: May 11, 2002 Location: NH Posts: 5	pressure I seem to remember reading that rifle loads w/SAAMI max's of 50,000-52,000cup measure 60,000+psi w/piezo electric transducer. I have never seen a comparision for lower pressure handgun loads and am hoping someone here has more info.

May 13, 2002, 03:11 PM	#5
222remmag Junior Member Join Date: May 11, 2002 Location: NH Posts: 5	pressure In general, I am asking if anyone has seen any data on tests of the same loads by the two different pressure measuring methods. I know that you can't convert one to the other.

May 14, 2002, 11:36 AM	#7
222remmag Junior Member Join Date: May 11, 2002 Location: NH Posts: 5	pressure Very interesting, Bob. Have you seen any published data?

May 11, 2002, 09:46 AM	#2
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	I've read conflicting comments about comparisons. I've read that there is no direct correlation; I've also read that CUP's are less than psis. Absolutely nothing more than a guess, but 32,000 CUP might be around 35,000 psi. I vaguely remember when the factories first started publishing CUP instead of psi. Rifles which had been quoted at 53,000 or 55,000 psi were then being quoted at some 49,000 to 50,000 CUP. Roughly. FWIW, Art

May 12, 2002, 12:30 AM	#4
Chemistry Senior Member Join Date: September 23, 2001 Location: Central Alabama Posts: 158	Unfortunately, there really is no direct way of converting copper crush units to psi.

May 14, 2002, 07:29 AM	#6
bfoster Senior Member Join Date: October 14, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	I've got both forms of test equipment, an old crusher gun and a Oehler system. Despite the common notion that psi values are always higher than crusher values for a given load this isn't always so, particularily with handgun ammunition. From the limited amount of work I've done with this cartridge, my notes indicate that with lead bullets in the 250 grain range, and slow burning powders (H110 & IMR 4227) a 32,000 CUP load will roughly be the equivalent of a 30,500 psi load. Bob