I agree with the bismuth recommendation. That's what I use in my heavy Scott 10. I use two wraps of watercolor paper to make a shot cup that tightens the pattern considerably in my cylinder bore gun.

For that matter, use black powder as well and shoot it like it deserves to be shot. It is way more fun than anything else you can do with it.

Brent

_________
BrentD, (Professor - just for Stan)
=>/

[Linked Image from i.imgur.com]