I too have the CMMG dedicated .22 LR upper with the correct 1:16 twist and the proper chamber, leade, etc.
Free-floated the barrel with a DPMS tube.
Then I added a Boonie-Packer magazine adaptor so I could use those wonderful S&W magazines, and have the bolt lock open after the last round.
Also added a Taccom recoil spring plug for good measure, and the system has been very reliable, along with pretty consistent one inch groups at 50 yards using Federal Auto Match bulk ammo.
...now where the heck can I find more reasonably priced ammo.