I really can't give you much more advice than what has already been given, which was good. Something is basically wrong with your reloading operation, whether it be mis-adjusted dies, bullet seated too far out and bumping the rifling, thick necks, or as I feel may be the case, elongated casings from not being trimmed properly or not at all. Check your loading manual for trim-to-length spec, and using dial calipers, make certain you are adhering to it. If you are loading without using dial calipers to check critical dimensions, you are playing with fire.