I understand your interest in exploring ball bearings as an alternative projectile for target shooting and even small game hunting in your .45 Kentucky rifle. It's great that you're finding them to be accurate, especially with your current sights and vision limitations.
So folks this is a thread from 2008.
Steel bearings also have the nasty tendency to bounce and ricochet on impact. Don't ask me how I know.
YES. YES they do they ricochet something fierce..., and it's rather disconcerting....
How about zinc/pot metal. It's even possible to cast at home. It has been talked about using that for rifles bullets. I don't know about cost though.
The problem with Zinc is the fumes when casting are highly toxic...
I think the marbles would be a good lead free alternative for small game If nessasary, think wrist rocket velocity or slightly higher.
Except that you might end up with glass shards in the meat.
One should look into Rotometals bismuth and tin combinations if one needs a lead free alternative, imho.
LD