The statement from the lawyer, about the gun, is one of the things that is confusing the story here. It appears from the 911 tape that Horn has the gun inside the house and is about to step out onto the porch.
I don’t know at what point he took the gun into the house. There may be an easy explanation, and it may be that it is a lie about the gun being kept in the truck.
It is a tragedy all the way around, but it could have been avoided if the burglars hadn’t shown up to do harm, and had harm done to themselves instead.
I think he retrieved the gun from the truck after he saw the burglars break in. That may have been before or after he called 911. He may even have been going to the garage to retrieve it as he was talking to the dispatcher. He racked the slide just before he said he was going outside, that much you can hear on the audio record.