20 Ga is a great deer gun. lighter to carry, not as much recoil, cheaper to shoot, and they have a flatter trajectory. I know what your thinking, bigger is better gotta get a 12Ga, not so. 20 Ga hit just as hard and at the same distance as the 12Ga,. But its all about going with what your comfortable, use what is a fit for you.
A Savage 20Ga slug gun in a bolt would be sick. I think Mossberg came out with some thing like that awhile ago in a 12Ga, but they went away in a hurry? Don't think they were very popular so they dropped it?