Use in kalifornistan - CMMG, Inc 22LR AR Conversion Kit, Echo

Have been using these for several years now, I prefer stainless over non-stainless (political correctness) model. Easier to see dirt and clean. If your AR is bound by state regulation of 'EVIL FEATURES' and you install this on your 5.56/.223 barreled rifle you are still mandated to have rifle KOMPLIANT. If you build the rifle with a DEDICATED 22Lr BARREL you can have all the Evil Features you can fit on that thing. The 22 barrel does give better accuracy out to 100 yards than the 5.56/.223 barrel will.
However, if you just want to shoot 22Lr occasionally or practice tactics and maneuvers without breaking the bank these conversions are an excellent option.
I recommend using the CMMG 22Lr Charging Handle, it prevents most of the Fail to Eject issues.
With younger shooters who may be a little apprehensive about firing a full on AR, I'll have them shoot and get familiar with the 22Lr converted rifle for 50-100 rounds. After they become confident and less stressed, I'll convert it back to 5.56 and allow them to take a couple shots. They are much more comfortable behind the rifle and less afraid of the perceived kick, (no kick). They usually want to burn a whole box of ammo by this time. More noise and no pain is appealing to the younger set.