A number of years ago I bought some UMC .44 magnum with cast rounds, and put them through my lever-action Browning B-92. After a few rounds I was getting really wild flyers, which was annoying because that carbine has always been unusually accurate in my hands.
When I examined the arm, there was a LOT of what appeared to be a talcumpowder-like grey residue in the receiver. It was LEAD, from the non-jacketed rounds I was firing!
It took me hours to get all that stuff out of the action, plus I had to de-lead the barrel, BIG TIME. I'd only put ONE tubefull of rounds through the carbine!
That really irritated me.
Most other ammo I've had has been OK the greatest problem was accuracy issues.