[RKB]

Porting does nothing to reduce recoil. From studies that I have read, the recoil pulse has been generated as the shot begins to move forward and clears the chamber/forcing cone area, long before it reach the muzzle. It might help with muzzle jump, but only if the porting is angled upward/backwards.
As for porting your Mossberg - save your money. It will not help you and it is not cheap.
Just my uk::two cents: