You foolishly go to town without your weapon. You have reasoned that a quick "jaunt" to the grocery store and back home... should be safe enough.
You approach your vehicle, groceries in hand. As you unlock your vehicle, a BG gets out of the car parked next to you....and is on you before you can react. He points a pistol at your upper chest, nearly touching you with the weapon. A woman nearby notices what is going on and screams. You take advantage of the distraction, move off line, grasp the weapon, and manage to disarm the perp.
You immediately rack the slide (not knowing the condition of the weapon) and cover the perp. while gaining distance.
Question: You are now armed, the perp. is unarmed. Are you "legally" justified to "threaten deadly force" by holding him at gunpoint. Think about it.