Ammunition Backpack

A Sub Trope of Awesome Backpack, the Ammunition Backpack is there if you use More Dakka, but don't have Bottomless Magazines, or just don't have enough space to carry more ammo in your pockets or Badass Bandolier.

Common for characters using hand-held miniguns (such as Blaine in Predator and the T-800 in Terminator 2) or other portable machine guns.

Also included are fuel tanks for flamethrowers, portable power plants for science fiction guns, and the like, and quivers for The Archer. In Video Games, you can bet that damaging the tanks will defeat enemies For Massive Damage.

See also Backpack Cannon.

Anime and Manga

 * Taken Up to Eleven in Hellsing Ultimate; For the final battle, Victoria's anti-tank rifle gets upgraded to a fully automatic belt-fed version and she uses a pair of them (with the approporiate reserve of ammo, many times her weight) to go Guns Akimbo against the vampire Nazi zeppelin
 * Played (kind of) straight with the Panzer Cops in Jin-Roh: The Wolf Brigade. While the MG42s that the Panzer Cops carry is fed from a loose ammo belt, their armor includes a backpack that dispenses extra ammo belts when the user needs to reload.

Comic Books

 * . The team battles the Cryonic Man, a villain with a backpack full of liquid nitrogen attached to wrist-mounted sprayers that he uses to freeze the Outsiders solid. They got better.
 * The Green Arrow's most famous arrow quiver is a wide rucksack design that covers his entire back.

Film

 * Predator 2. Peter Keys' team had "nitrogen guns" (liquid nitrogen backpacks attached to sprayers), which they planned to use to freeze (and thereby capture) the Predator.
 * More appropriately, they hoped to use the incredibly reduced temperature to effectively blind it during the capture, assuming (rather poorly) that it ONLY had thermal vision.
 * Let's not forget Blaine's Mini-Gun backpack magazine in the first Predator. Yes, it may just be an oversized magazine, but considering it's Blaine, Predator, and the whole awesomeness in general of that movie, well, it becomes awesome by proxy.
 * Terminator 2: for the minigun the T-800 uses against the police.
 * Lara Croft Tomb Raider: the title character could reload her pistols using a mechanism in her backpack.
 * The proton packs from Ghostbusters may count, as that's where all the particle accelerating goes down.
 * The packs from Extreme Ghostbusters definitely count, since the "wands" are proper guns fed by nuclear batteries stored in the backpack.
 * The Slime-Blowers from the second film definitely count.
 * The Matrix Revolutions had a variation on this with the humans' mecha, which would load ammunition ("knuckle-up") by lifting the guns behind them and magnetically attaching the chains. The ammo was loaded in a manner similar to an ammunition backpack.

Literature

 * Robert Heinlein's novel Tunnel in the Sky. Johann Braun had a powerful weapon called the General Electric Thunderbolt. He wore its power pack as a backpack.

Live Action TV

 * Red Dwarf had them for the bazookoids in the episode Polymorph. Also, one of the novels had them as the weapon's power source before it was retconned out.
 * In the 1960's Batman TV series, Mr. Freeze wore a tank of freezing gas on his back to fuel his Freeze Ray.

Tabletop Games

 * Several weapons from Warhammer 40000 are linked to a backpack, such as Imperial Guard hellguns, and various Space Marine weapons (heavy bolters, meltaguns). Space Marine missile launchers are not linked to the backpack, but in some cases it contains a reloading mechanism.
 * The PGMP/FGMP (Plasma/Fusion Gun, Man Portable) and laser carbine/rifle in Traveller had backpack power packs.
 * Paranoia
 * Flamethrowers and plasma generators. On the down side, a malfunction means they're about to explode, and the wielder must spend time unstrapping themselves before trying to outrun the blast radius. Hand flamers avoid it, but hold less fuel (and are only legal at Violet clearance).
 * The adventure "Send in the Clones" had an Ice Gun with its water supply in a large backpack instead of inside the gun as usual.
 * The Champions supplement Gadgets! included the following items.
 * The Plasma Gun, which was connected to a large backpack that contained its power source.
 * The Ice Sprayer had a supply of compressed liquid gas in a backpack Dewar container.
 * The Electric Gun had a large, heavy backpack generator/capacitor.
 * The Flamer was a flamethrower with fuel carried in multiple use tanks worn on the back.
 * The Sonic Disruptor had a back-slung power source.
 * 3E Shadowrun supplement Cannon Companion. The flamethrower's fuel was stored in tanks worn as a backpack and was delivered to the spray nozzle via a hose.
 * Iron Crown Enterprises' Cyberspace RPG had a number of ranged weapons with backpack power sources: the Gauss Rifle, Laser Rifle, Assault Laser and Heavy Laser.
 * BTRC's Guns! Guns! Guns! generic supplement (1996). Battery packs for man-portable laser and particle beam weapons could be carried in a backpack, connected to the weapon with a short power cable.
 * Star Frontiers. The Alpha Dawn expanded game rules had the Power Backpack, which could supply energy to fire weapons such as laser pistols/rifles, electrostunners and sonic disruptors.
 * Battlelords of the 23rd Century
 * The LTX-311 Chain Gun carries its ammo in a backpack.
 * Disintegrators use backpack mounted power supplies.
 * The Hot Chicks RPG had an Ammo Backpack available for all belt-fed firearms. It held 20 times the weapon's normal ammo capacity.
 * Laserburn Sci-Fi Combat Rules (1980): the Sungun carries its chemical fuel in a backpack which holds enough for six shots.
 * Manhunter. the Particle Accelerator Rifle was attached to a heavy backpack which stored the small metal pellets which were the P.A.R.'s ammunition and the energy that propelled them.
 * Mutant Future: most ranged energy weapons could have a Power Backpack as their energy source. It weighed four pounds and had a power cord that plugged into a weapon.
 * Terran Trade Authority RPG: the Power Backpack can be used as a power source for all portable energy weapons. It doesn't just store energy, it actually generates it, so it provides effectively infinite shots.
 * GURPS Technomancer:
 * The Portable Mana Disruptor had a backpack ERTG power pack and the Manpack Necrolaser was connected to a 20 lb. backpack battery pack by a heavy cable.
 * Flamethrowers have a backpack fuel tank.

Toys

 * The Super Soaker CPS3000 and CPS3200 both feature backpack water reservoirs with significantly higher capacity than any other water gun out there.

Video Games

 * The Ammunition Backpack in Starsiege Tribes, which doubles your ammo capacity. It's rarely used, however, since you end up sacrificing the ability to repair yourself, shield yourself, cloak yourself, or create a radar jammer.
 * Doom: The Backpack allowed you to carry double the ammo. This was very useful for the weapons with high fire rates such as the chaingun and plasma rifle.
 * The minigun in Resident Evil 5 comes with a HUGE backpack-o-ammo, whether it's being used by an enemy or Chris. It's actually somewhat problematic when you use it, since the huge backpack blocks off so much of your vision that large parts of the screen becomes obstructed while in aim-mode. But it does have the huge plus of both giving the chain gun it's ammo and it will also block attacks from the back, making it hard to get grappled or struck from behind.
 * Metal Gear Solid: Vulcan Raven wears a massive ammo tank for his M61 Vulcan on his back.
 * Certain enemies in Borderlands have ammo tanks which can be blown up (which is good, since these enemies tend to be the insanely powerful ones).
 * Team Fortress 2: The Medic has a backpack for his Medigun. Subverted slightly with the Heavy and Pyro; their ammunition is supplied by canisters on the weapons themselves. That thing on the Pyro's back is an oxygen tank, by the way, though the class selection picture has it connected to the flamethrower itself. The Scout seems to keep all his weapons in his messenger bag, and the Soldier has a small backpack filled with rockets. The Sniper, when using the Huntsman, carries a quiver of arrows.
 * Robotic example from Too Human - some of the 'Troll' class enemies use heavy Grenade Launchers, and wear huge, cylindrical ammo-canisters on their back to supply them. These are somewhat problematic, since their presence prevents you from doing your 'jump up on their shoulders and stab them in the neck' insta-kill, and they're hard to destroy since the Trolls always turn to face you ... hence, the grenade-launching Trolls winds up being much more dangerous than their hammer-wielding brothers, but not because of their attack-range...
 * Fallout 3 features an ammo backpack for many Big Guns, like the minigun or flamethrower, as well as a motorcycle gas tank for a Flaming Sword melee weapon.
 * Flamer units in Mass Effect 2 come with fuel tanks on their backs. Incredibly dangerous at close range as it almost instantly breaks your shields and can stunlock you to death. The best tactic to use against them is to snipe the fuel tank from long range, which causes them to flail around before exploding in a shower of gibs.
 * Incredibly dangerous, that is, unless you have the Incinerate or Overload tech powers. In that case, flamers are more of a threat to their allies than to their enemies.
 * Portal 2 showed one of the earliest models of the portal gun, it had a huge backpack used as energy storage.
 * Jorge in Halo Reach has one for his minigun. It doesn't slow him down one bit.

Real Life

 * Some flamethrowers require tanks to hold fuel. They are very visible and draw fire from enemy forces, and the fuel inside can be ignited easily if it leaks out (the wielder certainly wouldn't want either of those things) which is one of the reasons flamethrowers have fallen out of favour in combat.
 * The Russians developed a flame thrower with a fuel tank that resembled a standard ammo pouch, and built the nozzle to resemble a normal rifle. Flame weapons have been since outlawed by the Geneva Convention.
 * The US Navy SEALs and MACVSOG had [[http://seahound1969.hp2.jp/wswu/Uthin/SEAL
 * Arguably, quivers for archers count, when not worn at the belt instead.