>>518569617
You'd probably have to go the custom barrel and get like a 1:6 twist or better. I have a 300 blk AR with a 1:8 and I've never gotten better than 2.5" groups at 100Y. Add in a little wind and those groups balloon out to 4 or 5".
I shot subsonic 9mm out of a rifle at 100Y and you can blow that bullet a kiss and send it off by 3" at distance.