may want to try new shells as well as practice, bit upgrade the shells your using.
1625 FPS 3 1/2 inch are available.........called "Snow Goose" by Black Cloud.
Choke setup is really essential.
Also gives you confidence in th gun.
Simply place cardboard LIFESIZE rough cut outs of a duck, staple to a stick or something, walk them out 15, 25, 35 yards and shoot them. Even try a couple at 45, and 55 yards to see WHATS REALLY HAPPENING and how little shot is hitting them.....EVEN FIXED IN ONE SPOT !
If this doesn't work, I know a fine Chinese restaurant that has the best duck !