I've got some 45 cal minie balls that I put into a sabot and shot out of my 50 cal. Its a long bullet with a hollow base, so it ought to be very stable. As I remember they grouped real good, but I ran out of them. So I started shooting a 300gr. 45 cal cast bullet. But now that deer season is over, I'm going to play with the minie balls again, I cast a bunch about a month ago.