can anybody explain this one??? i need some help. i shot my new 458 wm. in cz-550 safari. the factory target showed a 2" group at 100 yards with jacketed ammo, and iron sights. the rifle was bore sighted at the gun-shop. i loaded 20, 440 gn. lbt hardcast gc wfn..459 diameter,the barrel slugged at 458 exactly, with 46 grains of xmp-5744. ( MARSHALL ) reccommends 50 grains of xmp=5744 to be maximum loads. wlr primers, o.a.l. of 3.025, the bullet started showing the rifling marks at 3.018". 5 rounds @ 3.010, 5 @ 3.015, 5 @3.018, 5 @ 3.025. every single bullet tumbled. some vertical, some horizontal, some at 45deg. point is none went in straight. i did not have a " M " die. the barrel was clean. i do not have access to a bore scope. to get a good look at the rifling. the forearm to barrel is so tight that i can't get a piece of paper under the barrel cold. i have not tried any smithing with it until i get to shoot some factory jacketed stuff. which should be here late this week. ( hopefully ) i've heard this before. if anyone has any ideas i sure would like to hear them! OH, BY THE WAY, as far as re-coil goes, i have shot a m-70, 30-06 that has worse re-coil with 180 grainers. to put this in perspective without any type of recoil reductions other than the factory pachmayer recoil pad. thanks all halfbreed