@yondu You have a loaded gun, how are they going to assault you?
Yes maybe they, if they were armed, could shoot you but you don't even know if they are armed.
It really would depend on the situation, if I thought there was reason for you to honestly believe that you were in danger i'd probably give you the benefit of the doubt. But too many people think they would be justified in killing someone because that person came onto their property and tried to rob them not because they truely felt they were in danger.

@BlueMetalChick Depends on the laws in the state where it happens. A young man and his father were home in Broken Arrow, Oklahoma and three men broke into the home and the young man shot them all, they died as a result.. The getaway driver, a woman, was seen on camera and taken in and arrested for murder because of her involvement, the man who shot the men were not charged because of Oklahoma's "Make My Day Law". The woman said that the men thought the young man was not at home and only the old man was there alone, no telling what they would have done to the old man if the son hadn't been there.

@yondu I think the court may find the justification of yours doesn't fit the means. Which I think in any court would translate to manslaughter, but I could be wrong and would be dependent in sentencing upon circumstance.

@Fishing65 courts also take what measure in self-defence you took in contrast with the real threat. Ie, you can't kill someone for yielding a butter knife when they rob your house and you pull out a gun.