I could see this being the case, but it's got to be very narrow timing, and it probably only applies for the same type of action.  A friend and I used to do a drill with his Glock 9mm.  (After ensuring the gun was unloaded) one of us would point the pistol right at the other's head.  The pointee would initiate action by grabbing the gun and the pointer would try to pull the trigger.  It was impossible to pull the trigger in time, action was always faster than reaction in this case.  We did it many times over, both of us with the gun. Semi-automatic handguns will not fire when you keep the slide from moving, which is what happens when you grab the whole barrel like this, though I don't think I'd be willing to try the maneuver in real life.