@shortstories - If someone is pointing the gun at your face... it's worth a try.
You would lose your hand, but very likely the gun would also blow up. Guns have been known to fail catastrophically when they are plugged with mud. So I would guess that a finger would have much the same effect.
It wouldn't stop the bullet of course. But the blockage would cause an extreme pressure spike as the propellent burns.
I am not willing to test this theory. 😅🍻