I'm in the process of making (attempting) swage dies for my BSSP press. I'm going for 40 cal, but if worse comes to worse, they will be repurposed for 45 cal. I'm working with O1 drill rod for the reamer and O1 tool steel for the die bodies.
What would be a good choice material for the top and bottom punches? I have a few feet of 41L40 along with the O1 drill rod and tool steel. I also have a bunch of stainless, aluminum and brass, but none of those would be good choices for punches haha. I did read somewhere that 41L40 quenched in oil made a good material for punches that wore well, but wanted to hear from the hive before I made them.