Ok...have to weigh in here...I bought a CMG 22lr upper (Bowers stocks them) and it works great on my "lower of choice". of course, I ended up acquiring a Plum Crazy lower just for this upper, but I didn't have to. I also acquired a Colt (Umarex) 22lr complete AR. I like them both though the CMMG upper is much easier to clean and completely functions like a regular AR. The Colt has a non-functioning Bolt release lever, but other then that works great. Both have great accuracy at 50 yds. FWIW...the CMMG BHOA has some difficulty with the polymer lower...it has more friction in the bolt latch area than the metal lowers. Takes some extra care, lubrication, and possible mods to function 100%