Good advice from Mohr. If you do end up going for the pump, I recommend the Rem. 870 over the Mossberg. Winchester is OK, too.

I prefer open sights for any kind of cover, as I have a hard time picking up stuff in the scope. If you're in cover I suggest a scope of no more than 3 power.

I have a Win. 1300 synthetic that I'd let go for 280, shipping included (assuming you're in the lower 48). It's got a rifled barrel and a barrel with screw-in chokes. The whole set-up is in pristine condition.