Rifle barrels must be 16" in length or longer.
+1 for shotgun for home defense. When I needed it, it was ready to roll, and the kid nearly shit his pants when I chambered a round.
+2 for buying a shotgun AND a .22 for fun. Ruger 10/22 can be pimped and you can have a blast with them.
I now have an M4 for home defense. But then again, I am not your run of the mill gun owner. I do not recommend them as defense guns to everyone. As stated before, the round over penetrates. However, if you buy an AR, and get a 9mm upper, then you can have the best of both worlds.