I know I can count on the experience here to answer this question, bolt has less than 400 rounds on it. Pictures are not the best sorry but the 2 bottom lugs at the rear show some deformation, one more than the other. Found it by accident when cleaning. Barrel extension looks fine, can this have been caused from the bolt riding over the rounds in the magazine?

2nd picture actually makes it look worse than it really is. Question is, is this normal.