uscra112 wrote on Jan 24^th, 2012 at 11:34pm:


I don't believe that headspace is the issue here.  The SAMMI pressure spec for the .32-20 case is 16,000 CUP.  Although there is no direct conversion from CUP to PSI, I would guess that the max PSI for this case would be less, and perhaps substantially less, than 30,000.

I also guess that a load of 13.0 grains of 4100 in this case would exceed 30,000 PSI by a fair amount.

Given the inherent weakness of the case, I believe that these relatively high pressures are causing metal to flow as the case is violently pushed against the chamber wall.  After so many firings, the case wall thins to the point that it separates.

JackHughs