Sorry for asking this every one but ive been trying to go over in my head how the good old gat-gun actually works. Is it an air pistol or does it merely work from the pellet being thrown from the action of the barrel extending forward at such speed and suddenly stopping( if I remember back to science that is kinetic or potential energy right?)

Personally I cant see how the pellet could be propelled by air due to the pellet pushing screw you place in the back, but I could be wrong