If you shoot a 1oz load @ 1100 fps the "Stock" could care less what the chamber presure is. Max Chamber Pressure affects mainly "The Chamber". By proper powder selection a heavier shot charge can be given a higher velocity without increasing chamber pressure or sometimes even lower it. The stock will be given more strain from the increased combination of shot wt::velocity irregardless of the chamber pressure.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra