I have an early 70's custom long rifle, given to me by a late mate and mentor, it had a Russ Hamm lock. My mate could never get it to spark consistently. Had a local gunsmith who is pretty handy with tuning flintlocks, changed frizzens, springs and hammer geometry. NO luck.
The rifle has a lovely Douglas barrel straight,.36 and is ver accurate. I have since fitted it with an L&R RPL drop in lock, from TOW, which did go straight into the mortice with minimal fiddling, it was tuned by a chap in Minnesota before being sent down under.
I heard tell of a Russ Hamm lock having a frizzed faced with depleted uranium and apparently would go off with a huge shower of sparks, but not to healthy to be around.
Cheers
Gordon