Re the comments concerning "approaching SAAMI" limits:
The shooter was using a recipe of 17.5 grains Clays. His loads were relatively consistent, a couple a little under, one a little over, one 0.3 grains over at 17.8. If we extrapolate from the Hodgdon data, which tells us that a 17 grain powder charge is 8200 LUP and an 18.4 grain powder charge 9500 LUP, then it looks like for each additional 0.1 grain of powder, the pressure increases by about 100 LUP. So, at the heaviest powder charge measured (17.8 grains), that would be about 9000 LUP. Add 1,000 to get psi: 10,000 psi. Yes, I'd say hot for a gun of that vintage . . . but still well under the SAAMI service pressure limit of 11,500 psi. And even under the CIP service pressure ceiling of 10,730 psi for a "standard proof" gun. I'd add that I've seen 9500 psi listed as the service pressure for old American 2 5/8" 12ga loads--but that was from pre-WWII sources, so it would actually be 9500 LUP, or about 10,500 psi. So the load should have been safe . . . but not by the safety margin most of us would like to see in vintage guns.
Glad to see other old-time vets chiming in with saltpeter as the supposed additive to Army chow to keep our raging testosterone under control.
Last edited by L. Brown; 02/05/14 06:20 PM.
