The 1:7 twist may lead up in the rifling and the gas tube.
(Original rifle non-issue when ceiner conversion designed "1:14 /1:12" twist rifles) Over stabilizing of the lead bullet causing less accurate shot group. Possibly more accurate with heavier/ subsonic ammo
I have a complete upper setup that I use, matching a upper I have with an ACOG. (It costs as much as a M&P 22 and then some.) I still have all the crud from firing 22LR in the lower, but the same trigger pull.
If the intended usage is 100-200 rnds I'd stick to a conversion unit if higher volume completely upper or rifle. I'm one that is a high volume use 300- 1200 rnds at the range.
