Chamber pressures for 12 Gauge VH

[Bruce Day]

Winchester still offers 20ga shells in 2 9/16" and 12ga in 2 5/8" lengths.

[gary cutler]

My sincere thanks to all of you for your information. One of my concerns was if the forcing cone was long enough to accept 2 3/4" shells without increasing pressures.
However, it would appear that the psi is low enough on the AA low noise, low recoil, target shells, that it shouldn't matter.
Gary

[J.B. Books]

Originally Posted by Bruce Day

Assuming Mr. Cutler's VH 12 is a standard for the type, his gun was intended for a service load limit of between 9500 and 10,800 psi. Not knowing present condition of the barrels, I make no current recommendations.

Bruce according to the Parker Proof Load Table you reference, your numbers come from "Theoretical Service Pressure Pressure Limits...." on the left side. As you can see that would mean 2 3/4" 12ga guns were built to handle 125% greater pressure than 2 5/8" chambered guns. That looks like a little chink in the armor that 2 5/8 chambers were meant for 2 3/4 inch shells to me.

[charlie cleveland]

some fine info here i will add to mydata book for sure...charlie