I finally buckled down and started some serious load developement for my .458. The trouble I'm having is that I can't seem to seat the bullets deep enough, that is, to 3.34". What's bothering me so much is that I'm using loads from the manuals that aren't listed as compressed or even at the top end! I'm using mostly Barnes X 450s and Hornady 500 grainers. I'm loading Winchester brass (new) and using a MTM drop tube (about 4-5"). The powder that's the best in my rifle is Varget. I can't get more than 70 grains in the case with the Xs and Barnes book lists 74gr as top end. Any suggestions?