My apologies to John Moses again.I am not here to get more enemies but to relay only my experiences compared too...

I have been lucky enough to know two people with pressure equipment for the 45-70..One with a pressure barrel with no throat and one with strain equipment hooked to a Marlin barrel.

There readings are virtually the same on some hot manufactured loads.

I also have one of the very first Guide Guns produced and you can get 2300 fps from a 300 grain Nosler.(The discontinued one) and be right at 40,000 PSI.

My other loads of a 350 North Fork can reach right at 2150 fps in my Guide Gun and be at 450 Marlin pressures...

The 425 and 525 grain cast hit 1850 fps(425) and 1515 fps (525) at below 35,000 PSI out of a Guide Gun.

This is all with "only" the right components and I never stray.

Jayco