You didn't say what powder you're using, that may be the culprit. In addition, make sure that every screw is tight on your scope rings and mounts. You may try changing primers, oddly enough sometimes that is all it takes. Use caution though if you are shooting max loads and drop the powder charge a bit. This is just a safe practice to excercise whenever you change components(bullets, primers, case, powder). In addition, you may try playing around wth the seating depth. Good luck