Jeff, you always grumble and fuss and swear the barrel is junk and then settle down and get the gun shooting better than ours do. I'm used to it by now, and all ready for it to happen again.
Cast bullets are their own world and a lot different from jacketed. Try some jacketed and maybe some factory ammo. Find out how it shoots with jacketed, and when you are ready to try cast again, the cast bullet shooters on the board will walk you through it.
I ain't in the least surprised by those groups. That's a little hotter charge than I would have used starting off with plain base cast. If those bullets are a bit small, as most commercial bullets are, bad accuracy is all you're gonna get. The pistol calibers aren't likely to shoot as well as the rifle calibers, anyway, but they'll shoot a lot better than that.