I recently purchased a DPMS SASS .308. I am having trouble developing a load for the rifle. I have been shooting 44g varget in fed cases with 168g hornady a-max. They have shot pretty good out to 1000 yards. That is until yesterday. All the sudden I am geting major pressure signs. Very distorted heads and poped out primers. same powder same temp. Today I pulled 7 of them appart to check the charges. I thought I was going to break the puller. It took forever to get the bullet out. Are fed brass harder? Should I tos the fed brass. Its once fired GMM?