Bumping shoulder back on 300 win mag

Amaturegunnut

Private
Minuteman
Dec 11, 2018
7
0
Ok guys i need some input. I am not new to reloading have several years under my belt. Problem is im having trouble. With bumping the shoulder back on 300 win mag case. The gun is a ruger m77 hawkeye LRT. New brass once fired. I set my rcbs fl die up for a 0.003 bump. But when i check the case in the gun its hard to lock the bolt down and when i eject the case it has half moon on the head of the case. I have never had this problem before. Cases are all trimed to 2.610.onec the case is fired the headspace is 2.272 so i bump it back to 2.269. But it tight when bolting down the bolt.any ideas
 
Take a sharpie and mark the circumference of the case just above the belt, and the shoulder. Then chamber and see where it’s interfering. Belted mag dies notoriously don’t size the area just above the belt enough.