Most complete one I've seen since wanting to get one. Need to order a rebuild kit I guess when the Fettlebox opens after the R&R. Duane
I'm with them, looks like a nipple for a percussion firearm. What it's not is a jet for your Hurlock.
Defiantly a nipple from a percussion cap muzzle loader. Interesting on how it got there, usually they are steel, yours looks like brass . Cheers Rob