ive got both. hands down the M&P. i even got a vortex strikefire red/green dot for my M&P. its a nite and day difference.
the cmmg kit is great for a lightweight survival hunting tool but its super super dirty in a standard ar15 upper. it works flawless but there is no comparison. the twist rate for 22lr needs to be around 1:16. ar15 barrels even the older 1:12 m16 barrels are just to fast.
get the M&P 15-22 you wont be disapointed. if you can find one get the magpul upgraded version its a pretty good deal
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent