Are you asking me to find the video of Travis Haley, shooting a suppressed subsonic 300Blk, out of a 9" barrel, using only a red dot, to hit his target at over 700 yards?
If you're just looking at accuracy, a 12.5" barrel will hit steel at 1,000 yards. Not saying the bullet would do much to a fleshy target at that distance... but it'll hit nonetheless.
Velocity helps against weather factors, but doesn't necessarily = accuracy.