The Firing Line Forums - View Single Post - Chamber Pressure in Regards to Cartridge Selection

Bart B. · November 11, 2012, 08:59 AM

Barnbwt, are those pressures in actual pounds per square inch (PSI) as measured by strain gauges, or are the copper units of pressure (CUP)?

I as 'cause far too often when CUP systems are used, the results are stated as PSI. There's quite a difference in actual pressure between them in the 50,000 CUP (60,000 PSI) range. Down in the 30,000 range for both, they're virtually identical. SAAMI specs for the .45-70 are 28,000 both CUP and PSI as shown in:

http://www.saami.org/specifications_...wnload/206.pdf

November 11, 2012, 08:59 AM	#4
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Barnbwt, are those pressures in actual pounds per square inch (PSI) as measured by strain gauges, or are the copper units of pressure (CUP)? I as 'cause far too often when CUP systems are used, the results are stated as PSI. There's quite a difference in actual pressure between them in the 50,000 CUP (60,000 PSI) range. Down in the 30,000 range for both, they're virtually identical. SAAMI specs for the .45-70 are 28,000 both CUP and PSI as shown in: http://www.saami.org/specifications_...wnload/206.pdf