I recall back when I owned the A. Verner rifle Taylor built, having he 48" Getz .50 bl. with round bottomed rifling, I used a .495" ball and the same 10 ounce Denim .021" that I am using my current Beck rifle with a Rice .50 "Gun Maker's Barrel" with square rifling, noted above. rifling twist is in the 60 to 66" I suppose. Really doesn't matter, as it shoots well with that powder charge, so that's what I use in it.