Incidently, .45/70 bras is actually stronger than most cartridge brass used in rounds that have SAAMI and CIP maximums of 64,000PSI to 67,000PSI.

Marlin loaded to 70,000PSI and the brass showed NORMAL pressure. Of course, the .605" rim is to a large part responsible for much of it's strength.

Even stronger yet, as pure strength goes, is .348 Winchester brass which is being used in my own .458 Alaskan, the .450 Alaskan and the .50 Alaskan ctgs.