"Its definitely no Ruger1. I have been told by people I trust you can load 45-70#1 using 458 win mag data. (I am not brave/stupid enough to try it) The #1 is crazy strong."
Well the Ruger #1 in 45-70 can handle the same pressure lever as the #1 in .458 Win. Mag. but no way can you put a .458 Win. Mag powder charge in a 45-70 case and still have room to seat a bullet. If you want 458 Mag, power buy a 458 Win. Mag. and be done with it.
The late gun writer Ken Waters opined that one could use Ruger #1 45-70 load levels in the 1895 Marlin. They'll work bit they hurt on both ends and you'll have the lever slamming open on every shot. I respect Mr. Waters and his knowledge of handloading but based on personal experience, he's dead wrong. Oh? And when that lever snaps open it gives your knuckled one hell of a healthy rap.
I can't speak on the strength of the Henry. Hell, I've never even seen one. I can speak on the Ruger #1 and 1895 Marlin though as I had both at one time. Sold the Marlin and the #1 is part of a small collection of #1s that range from .22 Hornet to .416 Rigby.
Paul B.