I have had no trouble shooing trap with my 18" barreled 870 magnum. I enjoy the looks of confusion I get when I pull it out of the case.
Gun has the factory barrel. Only mods are a +2 Wilson mag extension and follower, Vang safety, Tacstar six shot sidesaddle, and XS 24/7 banded front sight. Also chopped the LOP down on the stock and modded the pump grip so it clears the Tacstar. Everything else is stock. And it feeds everything I've ever run through it.