Just received my .54 Plains Pistol, may get it out tomorrow to test fire it. Looks perfect, the front sight was cast kinda lopsided but it should work. My .534 Minies fit way too sloppy, I carefully test fitted one and it slid in and dropped out when I lowered the muzzle. No good, can't use them. I think larger sized. 54 Minies like .538-.539 should work but I dont have any. I have a bunch of .520 and. 526 round balls , and two boxes of .54 Plains bullets so I'll see what I can get done. I don't happen to have any .530 balls. Hopefully the .520 balls and .15 patches make an easy loading , nice shooting combo.