Hey all. I just got back from the range and noticed a different wear pattern starting in my Ar. Never seen anything like this before. It’s just behind the locking lug recess. My only guess would that it’s from a cmmg .22 kit that I just picked up but I even sought that. It dig into the receiver pretty good but I still think it’s safe to shoot. Not sure what could of rubbed in that area. Here’s some pics and any thoughts would be appreciated.