I bought a new CZ 550 in .458 Win Mag nearly 2 years ago and it's never caused a jam problem.

I do load it long for the 500gn Hornady and the 350 Barnes TSX. In the Barnes I crimp in the bottom groove for a COL of 3.45". That's my hunting load for moose and black bear at 2750 fps. Shot a nice bl. bear with that load in September, 2009, at 90 yds. Frontal shot, complete pass-through. Bullet exited in front of right rear hip. Never found the bullet. I immediately chambered another round, as habit, and don't recall any kind of difficulty.

Bob

www.bigbores.ca