I have a Stag Arms LR-6, heavy bbl, 5.56 NATO and 1:8 twist; fewer than 500 commercial and surplus rounds fired. Accuracy has fallen off lately, obviously with expanding groups. Examination with a borescope revealed pitting/erosion at the muzzle end of the gas port with the eroded material deposited in the groove just forward of the port. Will this affect accuracy (I'm betting it does.)? Is there a fix short of re-barreling? Has anyone else had this happen?