I'd agree to try to steer clear of O1. It's often mentioned to treat it like a simple steel, but decent heat treating is relatively complicated. It has enough alloy in it that even careless drilling can spot air harden it and wreck a bit.
The thought I had about 'blue temper steel', and it should be confirmed, is because it is generally 1095 that has been tempered back to the low fifties (rockwell C), right about spring temper. It'll feel tougher than annealed steel, but it can definitely worked with regular home tools. Careful with creating too much heat while working it, maybe hold it with bare fingers and dip cool it as needed.
Another place you might be able find decent quality steel, that has known roughly spring temper heat treatment, is at a woodworking store. A plain flat cabinet scraper might also pick up a bit of thickness that full depth heat treated (not just the teeth) saws don't quite have. In garage sales and pawn shops, they're thrown in every now and then with screw drivers and old files. I think jump in, you can always send the gun out later if it doesn't work and you aren't altering either the broken part or some other part of the gun.
edit to add, 1075, 1080/84, 1095 are easy to come by annealed and would work with the heat to red and dump in old motor oil method, then maybe do one of the anecdotal oil burn off v-spring tempers? Best of luck.
Last edited by craigd; 04/30/20 08:10 AM.
