Know your target and what is behind it. -4 laws
I'm not superman and I don't have X-ray vision so I can't shoot unless I know where that bullet is going to end up.
There must be an immanent threat to life or severe bodily harm of an individual to use lethal force.
It's mighty hard to prove immanent danger when you've got a door between you and the person entering.
13 of 14 civilian (non Law Enforcement) armed encounters end without the need for shots to be fired. -Massad Ayoob
Better to be a good witness than to have to live with the fallout of firing too soon.I am not superman so I am not made of steel; and better to be judged by 12 than carried by 6.
Just because I'm not shooting through the door doesn't mean I'm not taking actions to defend myself before it opens.