Bob
If your left barrel shoots higher than the right, try grabbing the muzzles and twisting ccw as looking from the breach. The band at the muzzle is pinned to the left barrel and a bushing on the right allows the adjustment for point of impact, if the barrels are twisted a lot and stick they may shoot high and low. I'm sure it can affect how it shoots but don't know how much.
Mine shoots minute of white tail, 3" at 100yds With 405 cast, worked on a nice 4 point last fall.
Sparky