i have a bushmaster 1x9 superlight barrel, 16" preban, with bayo lug. 60 rounds fired. I want to trade if for a 1x7 16" chrome lined M4 profile barrel. DPMS, Colt, i don't care (prefer Colt, of course ;) ).
Alternatively, it's currently mounted on a flattop upper with bushy bolt, bolt carrier, etc., basically a complete upper minus rear sight. I'd be willing to trade straight across for a flattop upper with carrier and the above-mentioned M4 barrel attached.