Have you dropped the breech block yet to check and see if it's a cast or forged action? If it's cast the area below the barrel's chamber will be hollow. If forged that area will be solid. If cast I'd be very careful with loads, even in .25-20SS in a cast action.
By the way, your breech block is from a cast action as the firing pin screw is below the firing pin center line. If it was from a forged action the screw is above firing pin center line, like my forged Pacific is:

[Linked Image from i.imgur.com]

Last edited by Vall; 09/30/25 04:54 PM.