Hi Tinker, thanks for your reply. I used the "National Metallic" chamber casting alloy sold by Midwayusa. Funny you ask, I was actually considering casting the rifled portion as well, but then I had second thoughts because I wasn't sure if I could get the casting out easily. I did a chamber cast on a moderately pitted rook rifle a few months back, and had to really wail on the casting to get it out of the chamber.

Are you after groove or bore diameter? The rifling on my paradox is baby-bottom smooth, so I might just do it anyway.