If you did shoot someone with a shotgun or a crossbow, unless that person was carrying something with which they could reasonably be expected to succeed in killing you were they to attack, you would quite rightly be going to jail for murder. The fact that they are in your house is neither here nor there, as it should be. Being afraid because you have watched too much TV is no excuse for ending somebody's life.
Just imagine what the consequences would be if 'Castle Doctrine', the idea that your home is inviolate and you can kill anyone whom you claim was an intruder with impunity, was the law. You could invite someone into your home, after secretly breaking a window from the outside, and kill them - there are psychopaths who would consider that a legitimate way to advance their career, bankers and their ilk. I mean yeah, bankers so fuck 'em, but you get the idea...