or see were it shoots first then descide?
Work up some loads with .311 SMK's and see how it shoots first.
Mine was minute of angle, but they are long, thin, "whippy" barrels and can be very inconsistent.
I didn't want a barrel that long, and cut/re-crowned to 22", and it did improve accuracy slightly.
Longer barrels provide more velocity, they may be more or less accurate than a shorter barrel.