On night one with this instructor, I was just as skeptical as you are. It did not take many "sessions" (and sprained fingers, horribly sore shoulders, elbos, ribs, etc) , before he began to convince me. Part of his training is psychological. An armed assailant that intends to shoot will seldom touch you with the gun, he'll shoot you, end of story. This instructor did not have a lot he could offer you, in such a scenario!
BUT, when an assailant "pokes" a gun against your head, ribs, stomach, etc, he is doing it as a threat, and to control you, not kill you. He may change his mind and shoot, of course, but his first action has told you that at this point he is assuming that the presence of the firearm against your body, will give him complete control of you. Do nothing at this point to let him think otherwise, or you WILL be shot!
At this point you have to be very careful, but now you begin to have an opportunity to turn the tables, although as pointed out above, you would hate to get accidentally shot.
My instructor's first move now, was always to show fear, and compliance with the assailant, but also somewhere along the line one of his first moves in complying always had the effect of brushing that gun past his body, to avoid that first accidental shot, and then, instantly he accelerated to the point that I was disarmed, often facing my own weapon, and more often in quite a bit of pain. :shocked2:
It is hard to explain, you'd have to experience yourself. It's training, it's timing, it's effective