im just saying.......you probably bought a shotgun b/c you dont need a license and can walk out of walmart/sports authority with one upon making the decision you want a gun.
now just replay what happened to you at the door. where will the shotgun be? can you get to it? will it be loaded and ready?
you have to ask yourself, will the next time happen the same? will he get in? will he grab the shotgun when i pull it? will he take it from me and turn it on me? etc.
then if you want to even think about if you shoot someone, will you get charged? jail time? just things to think about especially depending on the state you live in.
if i had to recommend anything it would be a handgun, probably the small Glock. maybe even a tazer but I'm not familiar with them.
But in all honesty, if you were to do ANYTHING, keep a Louisville Slugger near the door and your cell phone. Some things should just be left to the police. First and foremost protect yourself and secondly be the best witness you can giving the police something to work with. You dont know how many times someone is asked "what did he look like we'll put out a notification" and the person says, "He was tall" and thats it.