The Cenier kit was the greatest accessory I got for my AR until I got a 9mm AR.
I guess .22LR is still cheaper than home-cast lead 9mm reloads, but 9mm is so much more fun! :twisted:
Still, it's a great thing to get if you aren't ready to spend $ on a pistol caliber AR or upper. If you live in the snow-belt, it allows you to shoot indoors during the winter, too. No having to find a range with a backstop rated for rifle rounds. Haven't tested the .22's out past 50m so cant comment on accuracy but it's great on an indoor/outdoor 25 & 50m range.
Bushmaster did make a dedicated upper for 22 but I dont know if it is still available. I tried to price one once but the distributor won't order any due to lack of demand.
I guess for the price of the kits, it's easier and cheaper to blow any powder and lead residue out of the gas system occasionally with a .223 round than to order a dedicated upper.
Either way, it doesn't have the kick factor of the .223 rounds but it's still tons of fun to shoot them cheap little .22LR's out of an AR! :-D
I remember way back when, one of the members of my old club brought in an auto (when they were legal) and let some of us throw a couple boxes of 50 .22's through it. :twisted: That was FUN because it was soooo cheap to fire the thing. 100 .22's was still less than 1/4 the price a box of 20 .223 at that time.