I have the conversion kit for a regular AR the thing is they don't do great in a fast twist barrel , not horrible but minute of squirrel head the hole head at 25 yards not well enough for my liking tried 1:7 1:8 and 1:9 the 1:9 was a little better. the best I could do was half dollar sized groups at 25 yards.
a friend has a 1:14 twist AR and his conversion kit works great for accuracy. 5 under a nickle at 25 yards
when I get to it I am buying the CMMG barrel and mounting it in an upper and making a dedicated 22lr upper (money) and some what hard to justify when I can get a 10/22 that shoots very well for 250 dollars 10 under a nickel
the conversion kit is good for plinking and shooting steel, just not little groups or scored slow fire targets
the dedicated 22lr barrels both 10/22 and AR are all 1:16 twist
if your looking for a AR like but not fully AR interchangeable ar-15 Style 22lr gun Tippmann makes a very nice one that will shoot competitive groups Appleseed worked with Tippmann to get these built and tested and they stand up to Appleseed shooting and accuracy the tippmann M4-22 http://www.tippmannarms.com/tippmann-arms-m4-22-elite-tactical-rifle/
the s&W M&P 22 was very popular at Appleseed but Appleseed tests every gun and shooters limits. the S&W AR- 22lr will and has fired out of battery sending shrapnel at the person next to ejection port , an issue when you are shooting with a line of shooters next to each other.
Appleseed documented this well and on multiple occasions and presented the issue to S&W and they stated the issue was chambers out of spec , guns were sent in for the recall and the issue remained after the recalled rifles were returned "fixed" they further documented it and presented to S&W and the issue was never resolved S&W said it is the out of spec chambers but doesn't want to do round 2 of recalls. Appleseed prohibits the S&W M&P 22 at their events until S&W resolves the issue , S&W doesn't seem to be interested in the issue.