Hello 500grains: My CZ550 is the standard magnum in 416Rigby. I have been using Federal factory loads with trophy bonded bear claw Plus some woodleigh weldcores. I have shot a few bears with it but have not recovered any bullets even on an end to end shot on a 400lb bear. I am going to get some barnes 350gr TSX and load some up for moose hunting.This gun worked fine right from the start no feed problems or anything. It is easy to strip the bolt for cleaning. As soon as I get a scope and load the 350barnes i will post the results. I have a 350gr mould but after getting it I decided the case is too large for cast bullets. Regards Dan