Hello everyone. I just wanted to ask those more AR experienced than me about this. When sighting in my new AR 16in bushy A3 w/ carry handle I noticed the Olympic 55gr I have will consistently not group as tightly at 25 meters as the Walmart value pack Winchester 55gr value pack stuff. At 25 meters the Olympic groups all over a 3 inch sticker target with most shots roughly center. The Winchester groups generally in a really tight group dead on center within a 1/2 inch if I am doing my part. Is this to be expected? Also, I have seen a rough spot in the chrome lining of my barrel, still there after approx 1000 rds with no change, about 1 inch from the muzzle in the side of one of the lands. The top surface the bullet touches on the rifling (the land) istelf appears to be OK and smooth, but the rough spot looks like a small chipped spot in the edge or side of it. Do not know why this happened, it was there when first purchased (new) and before cleaning it. Would this negatively affect my accuracy? Thanks in advance for replies.