Interesting Lee.

I just checked, and "0" buck is listed as .30 diameter. It's hard to get an accurate bore measurement on this small barrel without a plug. But it seems to be pretty close to .32 land to land, with fairly shallow grooves somewhere between .010 and .015.

So a .30 ball with .018 or .020 patches should do. Or does a thick patch like that "bunch up" in a small bore?