I noted that using the conversion formulas on post #10 on page one: CUP to PSI: =-17902+(1.516*(CUP)) and PSI to CUP: =((PSI)+17902)/1.516, seems to work fine for pressures above 33,000 PSI or CUP, however below that, the formulas produce questionable to nonsensical answers as one gets to lower and lower pressures.

As an example, using the formula on the following lower pressure pistol calibers, I got these low PSI results when converting CUP to PSI. Further, as the pressures approach 10,000 CUP, the calculated PSI are stupid.

Cartridge: - - - - Pressure PSI - - Pressure CUP (PSI should be higher than CUP)

.30 Luger ............24,546............. 28,000

.25 ACP .............. 19,998............. 25,000

.45 Colt (Ruger)....19,998............. 25,000

.45 Auto Rim......... 4,838............. 15,000

.44-40.................. 1,806............. 13,000

.38 Colt................... 290............. 12,000

And it also doesn't work well when converting lower pressure from PSI to CUP where the calculated CUP is higher than PSI, not lower. Further, as the pressures approach 10,000 PSI, the calculated CUP are stupid.

Cartridge: - - - - Pressure PSI - - Pressure CUP (CUP should be lower than PSI)

.45 ACP +P.......... 23,000............. 26,980

.32 ACP............... 20,500............. 25,331

.380 ACP............. 21,500............. 25,991

.45 ACP............... 21,000............. 25,661

.44 Special.......... 15,500............. 22,033

.45 Colt............... 14,000............. 21,044