You can short stroke a pump and cause some nasty jams as well.
It never fails to amaze me the people who will use a semi auto pistol and then avoid a semi shotgun like the plague. Like all autos....you need the correct ammo they like and keep a reasonable cleaning schedule. My Remington 1100 Competition Master is 100% with ammo above 1 DRAM/ 1 OZ. 22" barrel with tac latch, extended bolt release, fiber optic beads and big head safety.
The auto will be softer shooting and easier to shoot under stress (I've seen a LOT of police forget to pump the 870 in qualifications!). The Benelli's, Remington's and Winchesters are excellent choices. For a novice they are faster. For a trained shooter, the pump is almost as fast (there are excetional shooters who can run a pump faster, but I'm not talking about them)
That being said, the Mossy 500 and Remington 870 are rock solid. They are half the cost of a good auto and can take more abuse if you should choose to subject them to it.