Ditto on the clean and lube inside of case neck. Full length size and adjust die per instruction.

Check your bullet seating depth is not pushing into the lands. Black marker on bullet, neck, and shoulder should indicate the part of the cartridge that is causing the problem.

What brand of shell holder are you using?

Also read this post http://www.accuratereloading.com/ubbthreads/showflat.php?Cat=&Number=773000&page=1&view=collapsed&sb=5&o=2&fpart=1#Post774349 on this forum.

Do you lube the INSIDE of your case necks before you full-length size them? It is possible your expander ball is dragging in some of the case necks, pulling the shoulder forward enough to interfere with chambering.

i need help guys, my reloads are VERY tough to chamber in my gun some go in really easy some are so tough i have to through them away. Im using 270. sierra matchkings with 56 grains of h-4831sc this is 4 grains under the max and i trim all my cases to uniform length so i dont know what the heck is going on???