Buy a Ruger SR22 or SR10/22.
I have a couple different .22 conversion units for AR's, a dedicated .22LR almost always works far better.
[The most reliable .22 conversion, surprisingly, for me, is the USGI M261 with the .22LR inserts used in 20 round old GI mags. I run that in an old 20'' Colt GI upper with a 1/12 twist.]