I've shot minnies in .50, .54, & .58 and never could get accuracy out of them. In the ,58 for instance I think the barrel is .580-.582 diameter. The minnies are .577 which means they are slip fit. I tried paper patching them and every thing else. While they are fun to shoot they are not accurate enough for me. Now if I had say a 1861 Springfield Rifle which were a .577 bore, I understand that these minnies are pretty accurate. If I were you I would look at a .58 caliber maxiball.