I have a Bushmaster AR15A2 16" upper with the permabrake attached. Looks to be fewer than 1000 rounds down the barrel. Ideal for use as is for shorter rifle or SBR conversion. Looking to trade for similar quality A2 20" (or longer) barrelled upper. Trade of charging handle/BCG would involve charging handle and BCG being in the offered 20" (or more) barrelled upper. Might consider adding some cash for a higher quality 20" upper. Or, for that matter, would also be interested in buying a decent quality 20" (or longer) barrelled upper.