My hubby uses them to cast balls for his black powder rifle but they aren’t much use for anything else. The weights have too much other junk in them. Makes it too hard and will tear up your weapon. Could be used in an absolute emergency I suppose.
You can alloy cast wheel weights to make them suitable for any subsonic round. You can even use wheel weights to make good high velocity rounds with a gas check.
The problem is finding lead wheel weights. They are still legal in my state but most of the tire shops use the no lead variety because that is what their vendors supply now.
Even if you find a bucket of lead, you have to go through piece by piece to get rid of the no lead ones before melting them.
A real trajedy.