[aa1911]

My recommendation if you go shotgun is to have a buttstock rather than just a pistol grip. Gives you so much more control it's not even funny, really helps you point the gun. It may not seem like you need it in close quarters but it also serves as an impact weapon for last resort or less than lethal.

Mossberg 500 is good but you cannot upgrade the mag tube, 590 is ideal I think (very noisy action which is good!) with a light.