there are several variations of the MP15-22 that are threaded and equipped with flash hiders and other goody's. The magpul MOE grip lets me store a Otis 22cal cleaning kit right in the grip. This gun is not a .223 to 22lr conversion. it is strictly a 22lr. most ar15 22lr conversion kits wont shoot really accurate because the rifling in the barrel is made for 55grain or heaver rounds moving at several thousand feet per second not 36 grain 22lr moving 1200 feet per second. the upper receiver on the mp15-22 is not metal. the bold slides in to the upper and rides in two rails. the bolt is very easy to clean and maintain. my father has served in a special forces groups and worked for federal and state governments in a law enforcement setting and loves the mp15-22. He also used the military m16 22lr kits and is not a big fan.