Try some of his 420 grainers just for grins. I don't have access to a list of his molds right now (or ever) but I know he has a bunch of different .457/8 molds that could make a suitable conical. His computer was down for a bit or he would very likely haveseveral auctions up on Auction Arms. Even though the ones he lists on auction are primarily for centerfire rifle and handgun, many of them could be excellent in a .45 muzzleloader if cast in pure lead and sized properly.

Now half the thickness of a fingernail, I would guess that to be about4 RCH?