The RG&G Gatling gun uses 1/16" diameter firing pins, something like 3/32" nub on the end. I made mine by drilling a 1/16" hole in 1/8" drill rod, parted off the approximate length, then spot weld the 1/8" rod to the 1/16" drill rod. Then set it in a 1/16" collet and grind the OD and length of the nub. Granted, not a lot of use but have used it.
Bruce