If my state allowed me to carry rifles, I think I'd get a reliable autoloading shotgun, with a 10 magnification scope on riser blocks, so I can still use the sights for self-defense and clay shooting, and use the scope when I need precision with slugs. I also believe that for about $500, I could get something to let it use different ammo. (Though it might function as a single-shot with those, and I could but a different gun for less money)
But, since I can't, I'm thinking I'd get a g35, with .22 and 9mm kits. (I'm not sure if there are 9mm kits, but I think so)