The Gnasher Shotgun is a gun\weapon in the Gears Of War games. It is a pretty reliable weapon.
The Gnasher can kill at a fair distance. When not performing a headshot, or point-blank shot, the gnasher will down an enemy close-range with 2-3 shots. When headshotting an opponent, you normally don't need to aim, but you need to be within a good distance to do so. When you headshot the opponent, their head will explode regardless of your distance.