Excellent advice, Punisher.
Do what you honestly think you have to to keep from being injured or killed. Don't do any more just because the SOB deserves it and you're ticked at him. Once the threat is gone, don't keep fighting. Until it is gone do what's necessary.
My wife's cousins' grandmother (her father's brother's mother in law) told us how the neighbor came by one morning and said "Your grandson took my manhood away." The old lady was a little taken aback and was probably thinking of something anatomical involving garden shears.
It turns out the neighbor had gotten drunk and disorderly the night before. He was outside waving a pistol around and generally making a nuisance. Tiel's cousin came out to see what the commotion was all about. He kindly but firmly separated the gun from the man, unloaded it. Took the slide, magazine and cartridges and told the neighbor to go home and go to bed.
On the other hand, a very famous police officer was in an altercation with about half a dozen mobsters. There were several guns and knives floating around. He couldn't get to his. He figured he might need a gun, so he disarmed one of the bad guys only to find that he couldn't fire it. The man's finger was still in the trigger guard. If memory serves he hit a few people with the gun over the course of the fight.
If "Mongo" out of the classic police training scenario lost control of a weapon and I got a hold of it I would not hesitate to turn him into a Mongo-lace doily.
The scenario:
You have been called because an Emotionally Disturbed Person is causing a disturbance in an apartment building. As you climb the stairs you see the refrigerator come flying out the window of Mongo's apartment. As you near the door Mongo steps out dressed in bacon strips and a tinfoil hat. He picks your partner off the ground and head butts him into unconsciousness. Then Mongo turns towards you.
Q: What do you do?
A: Shoot Mongo as may times as you possibly can.