Just got a Double Star upper today. Looked down the barrel, noticed some crud. Tried to clean it out. Everything came out except the largest piece. I ran a bore snake through several times, no effect. Ok, ramped up to a brush on a cleaning rod. Better, but still there. Time for a patch. Hmm... still no better. Thats really odd.
Doing some searches on Ar15.com, leads me to believe I have a burr at the gas port. Do I need to do anything about it? It's basicly a noticable black spot on one side of the bore. I can tell that my brush, patch etc. was hanging up there. On AR15, it seems that they either believe it will wear down as you shoot, or you can remove the gas block and clean it out. How do I remove the gas block? It's a low profile gas block on a heavy barrel. There appears to be three set screws holding it on. Do I need to just remove those and pull it off, or is it something more complex?