I would walk out the door with my 20ga. tactical shot gun in my hand. That is plenty to eliminate any close in threat, and intimidate most people close enough to hear it. I never leave the house without a side arm. I would not walk into a crowd with my little daily carry piece though. It would probably be a Springfield XDM .40 or .45. On my back would be an AR15 carbine with laser and extra 30 round magazines.

If I thought I could scare them off, I might just walk out with an AK47 with a drum. Very intimidating, and effective at really close range.

I would not take any big bore rifle out to a street fight. The .30 cal. rounds are no more effective at close range than the lighter ones, but produce a lot more collateral damage. If they are far enough away to need the big guns, it's probably not self defense. Save the big ones for the deer and elk.