I load lower pressure loads, about 8500 psi, in 2 3/4 inch hulls for my 2 5/8 inch chambered 20 gauge Sterly completed in 1926. Even if there is a 1000 psi increase in pressure I'm below the loads that the gun was designed to shoot. I do try to keep the shot weight to 7/8 ounce and the velocity to 1200 fps to keep the recoil reasonable in consideration of the old girl's wood. But then again, she's just a spring chicken compared to my Joseph Lang which was completed in 1866.