I need to regulate the 20/22 barrels in my Baikal combo. 20 ga slugs are 8" high at 20 yds. How is the muzzle bushing attached? There is a pin, which indexes the 22 barrel(top bbrl), but driving the pin out does not loosen the bushing. Can't even see a line where the 22 barrel and bushing come together. Anybody??

Hitting this again---anybody know out there?? I calculate that I need to shim down the 20 ga barrel about .1" to lower the slug impact.