I have put maybe 100 rounds through a custom build Bear hunter in 300wm with no proble. I was having trouble with scope, put on new rings and took her to range. I put a few factors hornady american whitetail 150gr rounds through it and after thinking I wasn't on paper, I realized the bullets are blowing up at the muzzle throwing shrapnel down range. It does have a muzzle adjustable muzzle break on it. Break was on. Any clue guys?