My Lyman .54 Greatplains shoots 430g maxi-balls way better than anything else I tried in it, and that's been most everything. The rifle is close to 20 years old, and has 1:48" twist as best I can tell. Ran into a guy at a gun shop last fall, he overheard I shot a .54, and said he had just bought a bunch of bullets at an auction with some other stuff, and didn't need these. I'mnow well stocked.