I have a dedicated 22lr AR...It's a superior arms complete lower mated with a Tactical Solutions (Tac-sol) complete upper.
It's got an alloy "bull" barrel with a steel liner, and like many tac-sol barrels it is very light and accurate--has gone sub .250" at 25yds.
I've use black dog machine 25rnd magazines.
I get about failure 1 in 100rnds using the cheapest of the cheap--old $7 per 550 federal bulk.
With good quality ammunition the failures pretty much disappear. It can usually go over 500rnds before it needs a good cleaning.
Not cheap, with an MSRP above $550 for the upper...but it's a ton of fun to shoot, and much more accurate than using a conversion in your existing upper. Given the rate of twist in most .223/5.56 (being 1:7-1:9) 22lr does not stabilize and it'll usually look like shotgun patterns at 25yds.