I had a few problems with my Puma in 44 Mag. until I re-slugged the barrel. Since SAAMI groove dimensions are different for a rifle (.431" vs .429" for handguns) all my cast bullets were a bit small at .431"-.432" for the .432" barrel so I just opened up a Lee sizer to .433" (+ a hair). I now use Ranch Dog bullets sized to .433" and they work fine. I didn't do a chamber cast but all my cast bullets in mixed brass will chamber fine.