A shotgun is known to be powerful enough to kill Bowser in one shot (but beware- he will come back to life to kill you). It is a very strong weapon that can blow through metal. Meaning T-5000 (but not the T-5001) is defenseless against a shotgun. Also, it is good for hitting people upside the head with. Recent test have shown that it to be highly effective against Evil Snowmen. Unfortunately, it can not be used long distance, and you must be right in front of the target. This presents problems.
It's power doubles when you add another barrel, giving it the name of either Double-Barreled Shotgun, Super Shotgun, Scattergun, etc. I think Doomguy likes it.
Side effects include flying into walls, quick deaths, painful deaths, unbearably painful deaths, explosions, bloody nose, broken bones, evil laughter, reloading, destruction, pain, papercuts, screaming like a little girl, getting Germany mad at you, and lists of side effects.