That doesn't surprise me from what I've already seen and heard about these actions, and those factory versions weren't even made from 4140!

My 45-90 was built as a "thick side" and has a heavy Green Mountain octagon barrel that started out as a 1.27" round blank but it has the 15/16" shank, the one I am building now has the 1" shank that I wish I had of chosen for the first one. Still I proof fired it using 458 Magnum mid-range loads (near identical case dimensions) which is substantially higher pressure than anything I will ever shoot in it again and it handled those with ease.