A shotgun has the advantage of that nice sound it makes when you rack a shell into the chamber. If that doesn't make the scum crap themselves and run for the door, then you probably have a fight on your hands.
I would suggest watching some videos on tactical use of a shotgun as well. There are a couple of shell handling and quick-loading techniques that everyone who owns a shotgun for defense should know.
For example: unloaded pump shotgun, slide back with chamber open, holding the grip in right hand. With a shell in your left hand, primer end against your pinkie, business end against your index finger, reach under the gun and flip the shell into the open action port on the side, then slam the slide forward.
You have a round ready to rock while you fumble around loading more shells into the bottom of the action. This also increases your shell capacity +1
You can buy dummy rounds to practice loading with.