I have 2 nephews that have finished their Eagle Scout award and I would like to reward them with shotguns. They are city boys, very casual shooters, and off to college and may not shoot enough or be interested enough to acquire other guns for many years to come so I would like them to be covered for Deer, birds, and clays. I am somewhat familiar with Mossberg 500 and Remington 870. What other guns are available with barrels you can switch out? Pumps and Semi Autos only please. Id like to buy something better and more expensive than an 870 but not break the bank.