Chiappa Firearms M4-22 Upper (.22 LR AR-15) Posted June 24, 2011 in AR-15, Rifles by Steve Johnson with 23 CommentsTags: 22, ar-15, chiappa, rifle, rifles Chiappa Firearms is now selling a AR-15 upper chambered in .22 LR. The M4-22 is compatible with all mil-spec AR-15 lowers. It has a 16″ barrel, weights 3.5 lbs and is shipped with two 28 round magazines. The MSRP is $349. Win a Kel-Tec PMR-30 !!!