Brass isn't a problem with the 45-70.George Weber of Hodgdons powder tested Winchester brass(The thinnest of 45-70 brass)at 70,000 CUP and they just fell out of there SAAMI barrel.The action is the week point in the leverguns not the brass..

Hodgdons rates the Ruger #1 at 50,000 CUP but I understand how one could assume it would take the same pressure as the 458 Win Mag in the same firearm,somewhat like my BFR in 45-70 which has an interchangeable cylinder to take the 450 Marlin and it's SAAMI of 43,500 PSI.

Jayco