Both barrels are full choke, so more than likely it isn't the lack of shot that is not bring the birds down but not centering the shot on the bird.
Large shot, more shot, has the thought of not shooting if the bird is beyond the your ability to center the load on the bird. More than likely hours spent on the skeet, trap and sporting clays course shooting from a low gun position with the safety on as you would be in the field when a pheasant flushes would do a lot more for putting birds down than adding more shot.
Opening your first barrel to IC or LM might be an option also.
Last edited by oskar; 07/23/19 09:29 AM.