The PRO SERIES MAGNUM GOBBLE DOT (TG944 series) was designed with a generous amount of elevation adjustment. It is important to mount the two sights as far away from each other as possible to maximize elevation adjustment.
The rear sight needs to be brought as far back on the rib as you can, without coming past the barrel onto the receiver and it is also important for the bottom of the sight that it does not contact the top of the barrel. You will also need to shoot with a full face contact to the shotgun’s buttstock comb to ensure you are getting your line of sight low enough.