Actually Colts are considered pretty good - if you're talking mostly about pre-bans. There are more Colt pre-bans around than any other brand - they made more. Their chrome-lined service barrels are considered some of the best of this type (I would not have any other on my M4). But lately, Bushmaster, Armalite, and Rock River have been turning out very nice rifles, while quality and especially customer service from Colt has been dodgy. RE:conversion, the BM will accept the RDIAS unmodified, so it is preferred for that by the class-3 RDIAS guys, but for the rest of us it really makes no difference. Colts often are not made to accept the standard pushpin up front, and the hammer and trigger pins are bigger on Colts since the blue-labels came out.