I've been searching for a nice little plinker .22 that would simulate AR-style training without all the added expense of ammo. This is what I've found Colt M4 Ops .22 This looks like a newer model style AR-look-alike, and appears to be pretty rugged as far as materials. I was thinking either this or a CMMG conversion for my upper. What are the pros and cons of each? Thanks!