I experimented quite a bit with my Bill Large .58 barrel using patched round balls, but also several of the Lyman Minnie moulds from the 315gr. up to the 570gr. mould.
I shot them all, lube in the grooves only, can't quite remember what lube was used, but something like a mix. of lube 1000 with beeswax. I had no fouling problems, even
after turning the base plugs for thicker walled Minnies so the walls wouldn't blow out from muzzle blast due to the powder charges I was using. This was in the later 70's.
Pretty much all of my shooting was at 100 yards, benched with bags. The .575213OS (Old Style) was my favourite with skirt thickened a bit to weigh 480gr. The 580gr. Lyman
#57730 altered to weigh 675gr. was best for 100yard accuracy using 150gr. and 160gr. 2F of 1977's Gearheart Owen's, giving 1,250fps and 1,325fps respectively. These were
sub 2" up to 2 1/2" loads. They were the result of my reading about Val Forget shooting an elephant with a .58 rifle with modified Minnie and 175gr. 3F- article in the Lyman book.
All bullets shot bare.