A tranquilizer gun (or tranq gun) is a handheld firearm whose ammunition is non-lethal, and used to knock enemies unconscious. Tranquilizer guns in the Metal Gear Solid games include:
- M9 - a modified Beretta 92F/FS used by Solid Snake and Raiden in Metal Gear Solid: The Twin Snakes and Metal Gear Solid 2: Sons of Liberty, respectively.
- Mk22 - used by Naked Snake in Metal Gear Solid 3: Snake Eater, Big Boss and his resistance in Metal Gear Solid: Portable Ops, and the Militaires Sans Frontières in Metal Gear Solid: Peace Walker.
- EZ Gun - also used by Naked Snake in Metal Gear Solid 3 and Peace Walker, although in the latter, it appears as a special support item.
- Mk II pistol - used by Solid Snake in Metal Gear Solid 4: Guns of the Patriots
- Wu Silent Pistol - used by Big Boss and the MSF/Diamond Dogs in Metal Gear Solid V, both with Metal Gear Solid V: Ground Zeroes and Metal Gear Solid V: The Phantom Pain.
Tranquilizer guns are extremely effective in that they are a suppressed, non-lethal way, to temporarily eliminate an enemy threat. Metal Gear Solid 2-4, Portable Ops, and Peace Walker all have a tranquilizer guns in their game. It has been confirmed through released gameplay that Metal Gear Solid V: Ground Zeroes and The Phantom Pain will have a tranquilzer gun. It is unknown if it has customizable attachments like other, more lethal weapons.
Behind the scenes
In Portable Ops and Portable Ops Plus, the ammunition containers for the Mk22 and Mosin Nagant (9mm T and 7.62mm T, respectively) display a star and crescent, presumably to symbolize nighttime.
In Metal Gear Solid: HD Collection, hitting 100 soldiers with tranquilizers in Metal Gear Solid 2 will result in the unlocking of the achievement/trophy "Don't Taze Me, Bro."