I have the CMMG kit and it works flawless, I also use the cheap winchester 333's or 555's in it without any issue . I have not had good luck with the remington .22lr ammo in it its under powered and doesnt cycle every time. CCIs work well but of course they are more expensive . I have also had decent luck with the federal bulk stuff except maybe 10-15 misfires out of a box of 500 . Also have used the aguilia rounds without any issue . on sub sonic stuff you need to research it because some are not meant to cycle semi auto rifles. Aguilia makes a 60 gr subsonic in .22lr that cycles a AR just fine and they are more accurate in the tighter turning barrels.
Just remember this .22lr ammo is dirty , I started losing tight groupings at around 700 rounds and it had to be cleaned and deleaded with some lead removing chemicals. Also there is alot of unburnt powder and crap that comes back thru the gas tube shooting a couple .223 rounds when your done will clean up the gas tube . One last thing you will have to clean the guts of the lower up every once in a while and the bolt and chamber will need more cleaning also . .22 lr is just plain dirty but it sure makes it cheaper to shoot and is just as much fun