A few decades ago, I won a Ruger Red Label 28 ga. and a Remington 1100 20 ga, at the same DU Banquet. I took my two young sons out to shoot the two new shotguns. And everyone commented how the 28 ga. Ruger O/U kicked more than the Remington 1100 20 ga. Both were loaded with Win AA target loads, so other than the 1/8th oz. of shot difference, the velocity was consistent. A friend had a Ruger Red Label 20 ga. and his complaint was that for a 20 ga. it kicked hard. I really like how the Ruger Red Label 28 ga. swings, and fits me, but it does bump one harder than a 28 ga. should. I have a Beretta A400, in 28 ga. and it definitely has less recoil than the Ruger.
If you are shooting skeet, ever consider going to a smaller bore shotgun, and possibly a gas operated semi-auto? I shoot trap with a 12 ga.(A Citori for nice weather, and a Maxus, with added weight, for rain), but for skeet I shoot 20 ga. or 28 ga. depending on my mood for challenge.
I do agree with the recommendations to get your gun fit checked. But starting with a softer shooting semi-auto, gives you a good base line to work from.
Squeeze