If the drawings are from the Ballard Rifle Co. they are practically worthless. I tried to make a Ballard hammer from the drawings and could not get the dimensions to match anywhere close enough for a waterjet program. Had to entirely redraw it. SSShooter had some set triggers made from the drawings and the rear trigger was close but the front triggger was no where near correct. They are pretty and should be used as reference only as many dimensions are not correct.

What would be a good material to make one from? 8620 or A1 or A2 etc...?




JMH

I'd concur with O-1.  I made some hammers and triggers years ago out of "sheffield steel", which is essentially O-1.  As I noted in my post before, you have to draw them out after quenching, or they will be too hard and chip.   

If I could get it in the right thickness, I'd also try 4140 pre-hard, if I was going to blue and not case it for finish.  I think it'd be close to right, as is, and wouldn't require heat treat.  It'd be a compromise though, the sear wouldn't be quite as hard as I'd like.

If you are going to case color the hammer, 8620 would be a good choice.  I might add carbon to the sear area with Casenite before the case color though.  O-1 and other higher carbon steels would be too brittle after case hardening.