AAHHH GUNS The only way your going to ward off any BIG animal with a shotgun is to use the gun as a club and hope you out last the animal or to use a high grain slug round and double O-buck and thats only good for a couple hundred feet at best.
A semi-auto 12 gauge 30 inch barrel with a load tube that holds 6-8 rounds would be best loaded with two types of rounds alternate rounds between (slug - doulbe O-buck - slug - double O-buck and so on) that will maximize power with pattern. Your still gonna get up close and personal with what ever is looking for lunch.
Dont waste your money on a Benelli, they kick like an old mule, cost more and they are no better than anyother gun. A Remington 11-87 is a great shot gun and alot less money. (personaly I have owned both and stand by the Remington) has never let me down once. Another down side is that a shotgun is slow to load when you are in a hurry.

If your looking for something for protection look into a .30-06 or 300 win-mag rifle. With a rifle you can carry a loaded clip and it takes only seconds to be ready to fire, both very dependable rounds and they will knock a bear on its ass for sure. (as lonag as its not a gut shot) any large animal with lunch on its mind is going to go the distance if its not hit in a kill zone.

Something a little easier to carry in a side x side would be a 44 mag or 45 handgun, lots of power for large animals (not the best) and not easy to aim in a hurry and just might break your rist on the second shot.
I carry a 40 s&m Sig-Sauer P229 on my Rhino. Light and accurate and it holds 12 rounds in a clip. (Not good for larger anaimals thoe.)
MY SIG

Lastly, thank god we still live in a country that alows us the FREEDOME TO BEAR ARMS , with the correct permits you can carry a gun (just about) anywhere anytime. I just dont your local laws on a loaded gun. In Maine you can carry a gun anytime as long as its not loaded unless you have a concealed gun permit.