I’d like to see what other guys using their flintlock muzzle loaders will do. I have a couple muzzle loaders a 54 and a 50. The 54 has only been shooting mono bullets (lead that is). The 50 is a newest model 700 which I bought to hunt elk in New Mexico - in that I’ve shot a few different types of bullets.
I doubt my 54 will ever see copper bullets though, at least in my hands.
If the federallies say I have to shoot something other than lead in the 54 they won’t have permission to step foot on my land in muzzle loader season.