Radkins wrote on Dec 24
th, 2015 at 11:35am:
With properly heat treated 4140 I would venture to say that receiver will have strength capabilities right up there in Ruger No. 1 territory. The Highwall is of course an inherently strong action design anyway and when combined with the fantastic strength properties of 4140 they become almost indestructible! Of course watching for stress risers that could lead to cracking makes a big difference, such as correct radius of the breech block mortise corners, eliminating sharp corners and edges in the extractor relief, etc but then those are just precautions with any rifle.
Someday I would like to test one of these things to destruction just to see what it would take, from what I have been told and read about concerning the strength of the design I expect it would take a LOT!
BTW, have you selected your wood yet?
A couple weeks ago, I played around, heat treating / tempering some scraps of 4140 - was amazed at how hard and tough it got. Tried breaking a piece ~ 1/4 x 3/4" in the vise - took a 4 lb. hammer and a few quite strong blows !
For wood, I have some Cherry wood from a tree I cut down in my front yard that I'm going to try.
For barrel, I'm torn between just buying a rifled blank, or building a rifling machine and making my own.
In the #2 Campbell book on Winchester single shots he re-prints an article on intentionally "blowing up" a highwall. I don't remember the exact charge they used but it was quite a large "over charge" of 4064 IIRC (like almost 30% over) and it blew the firing pin out the back and broke the hammer but I think the breech block and receiver were still in place.