We can only use 2 3/4" with 9 pellets over here and they generally pattern poorly.Its a shame we dont get the variety of choice you guys get.
Go to a gunsmith and have the frocing cone in your shotgun lenthened.
And it will improve the pattern.
Plus it will feel better on your sholder.
Most factory shotguns have about 1/2 inch forcing cone.
If it was lenthened to about 1 1/2 inches,
it wouldn't deform the pellets and pattern batter.
Good Luck