A good idea, but I'll disagree, strongly, that no one really knows. It's simple: Articulate that the other guy has the means, opportunity and intent to cause you serious injury or death. If you're in a weird place requiring retreat or other preclusion, explain why that wouldn't work for you. The fact that he had the means until he dropped it, or that they had the means until part of the posse fled or got killed, doesn't count. Show that all the elements exist when you pulled the trigger.