BG points a gun at you at contact distance and you attempt to disarm him before he can squeeze the trigger. Anyone can do it. Action is faster than reaction.
He who hesitates is lost . It is easy to underestimate the amount of time it takes for sensory information to enter your brain, process, and then the resulting action command to be sent from your brain to the muscle charged with contracting your index finger.
There are three "tricks" to a successful disarm (and this applies to any contest of reflexes).
1. Don't telegraph your move. Any sort of "set" or pre-cursor to your movement will give away your intention.
2. Economy of motion. You have to take the shortest route possible to the weapon. That means no wind-up, and no wasted motion.
3. Move your whole body as a single unit. If only your hand moves to reach for the gun, you're going to catch a bullet. As you reach to control the weapon, you have to close your centerline (making yourself a smaller target and putting more meat and bone between the muzzle and your vital organs) and move clear of the line of fire.
Bottom line is, you've got a pretty good chance of being shot regardless of what you do...hopefully it'll be and exremity hit or a glancing shot, and you'll be able to keep your wits about you. If you make your play and take a bullet to the shoulder, you'd better stay on the attack...make it your soul purpose to control the weapon and bite that jerk's nose off. Odds are the gunman isn't going to give you a second chance if you back off and call "time-out".