Quote Originally Posted by sharpshooter View Post
The pin itself is made from 8620 leaded and is case hardened to R15N 90 min, .006-.010" case depth. If you don't recognize those numbers it's because it's a scale just for case hardening. It's the equivalent of 56 Rc. I'd just use O-1 drill rod.
I'm pretty sure I have some O-1 or W-1 in 1/2" around the shop. Hopefully I'll have time tomorrow to take the bolt apart and look more carefully at and measure the parts.