Got mine at Cabela'a in Buda, TX. Out the door for $350 I think it was, a few years back. What a sweet pistol! Definitely my favorite gun to shoot, just needs a free afternoon so I can spend the necessary 5 hrs cleaning afterwards!
I use .451 balls as well. They always get that circle shaved off goin into the cylinder, so I don't need any bigger than that. And #11 caps.
I'm not sure what I'm doing differently, but I can't fit near 60 grains into that chamber, by the way. It's been awhile now, but I think I'm using FFFg pyrodex, not sure what brand.