[[quoteright:300:[[Anime/JinRohTheWolfBrigade http://static.tvtropes.org/pmwiki/pub/images/backpack_4016.jpg]]]]

A SubTrope of AwesomeBackpack, the Ammunition Backpack is there if you use MoreDakka, but don't have BottomlessMagazines, or just don't have enough space to carry more ammo in your pockets or BadassBandolier. Depending on the size of the backpack, the wearer may become a MightyGlacier due to the weight slowing movement.

Common for characters using hand-held [[GatlingGood miniguns]] (such as Blaine in ''Film/{{Predator}}'' and the T-800 in ''Film/Terminator2JudgmentDay'') or other portable machine guns. Also included are fuel tanks for [[FireBreathingWeapon flamethrowers]], portable power plants for EnergyWeapons, and the like, and quivers for the ArcherArchetype. In VideoGames, you can bet that [[AttackItsWeakPoint damaging the tanks will defeat enemies]] ForMassiveDamage.

See also BackpackCannon.
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!!Examples:

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[[folder:Anime and Manga]]
* Taken UpToEleven 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 appropriate reserve of ammo, many times her weight) to go GunsAkimbo against the vampire Nazi zeppelin
* Downplayed by the Panzer Cops in ''JinRohTheWolfBrigade''. Their backpack stores ammo for their [[MoreDakka MG42s]], but instead of it being a rack for a [[BottomlessMagazines continuous belt going directly into the gun]], it lets the user pull out individual belts to be loaded into the gun, sort of like a paper towel dispenser. For bullets.
* The Hajime Katoki redesign of the [[Anime/MobileSuitGundamWing Gundam Heavyarms]] features a huge ammo drum the size of the mech's torso.
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[[folder:Comic Books]]
* BatmanAndTheOutsiders #6, "[[http://static.tvtropes.org/pmwiki/pub/images/Batman_and_the_Outsiders_Vol_1_6_7784.jpg Death Warmed Over!"]]. 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. [[HarmlessFreezing They got better]].
* The GreenArrow's most famous arrow quiver is a wide rucksack design that covers his entire back.
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[[folder:Film]]
* ''Franchise/{{Predator}}'' franchise:
** Blaine's Mini-Gun backpack ''magazine'' in the first ''Film/{{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.
** ''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.
* ''Film/Terminator2JudgmentDay'': for the minigun the T-800 uses against the police.
* ''Film/LaraCroftTombRaider'': the title character could reload her pistols using a mechanism in her backpack.
* The proton packs from ''Film/{{Ghostbusters}}'' may count, as that's where all the particle accelerating goes down.
** The packs from ''WesternAnimation/ExtremeGhostbusters'' 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.
* ''Film/TheMatrixRevolutions'' 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.
* Hawkeye's quiver in ''Film/TheAvengers'' actually has the shafts separate from the [[TrickArrow various arrowheads]], with a rotating carousel that gives him exactly the head needed.
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[[folder:Literature]]
* Creator/RobertAHeinlein's novel ''Literature/TunnelInTheSky''. Johann Braun had a powerful weapon called the General Electric Thunderbolt. He wore its power pack as a backpack. The large metal backpack serves the colony well long after it stops functioning as a power supply for a broken weapon.
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[[folder:Live Action TV]]
* ''Series/RedDwarf'' 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 ''Series/{{Batman}}'' TV series, Mr. Freeze wore a tank of freezing gas on his back to fuel his FreezeRay.
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[[folder:Tabletop Games]]
* Several weapons from ''TabletopGame/{{Warhammer 40000}}'' are linked to a backpack, such as Imperial Guard hellguns, Ork deffgunz, and various SpaceMarine weapons (heavy bolters, meltaguns). Space Marine missile launchers are not linked to the backpack, but in some cases it contains a reloading mechanism.
* ''{{Traveller}}''
** The [[{{BFG}} PGMP/FGMP]] (Plasma/Fusion Gun, Man Portable) and laser carbine/rifle had backpack power packs.
** The ''Dragon'' magazine #116 article "Aim and Burn" has several flamethrowers, each with their fuel supply in backpack tanks.
* ''TabletopGame/{{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 [[OutrunTheFireball 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.
* ''{{Champions}}'' supplements
** ''Gadgets!''
*** 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 Force Field Neutralizer carried its power supply in a backpack.
*** The Sonic Disruptor had a back-slung power source.
** ''Enemies''. The supervillain Blowtorch had a flamethrower with its fuel in a backpack.
* Some heavy and directed-energy weapons in ''TabletopGame/{{Shadowrun}}'', like flamethrowers and laser cannons, require lots of fuel. If the weapon isn't vehicle-mounted, then the wielder is likely carrying all that fuel on his back.
* Iron Crown Enterprises (I.C.E.)
** The ''Cyberspace'' RPG had a number of ranged weapons with backpack power sources: the Gauss Rifle, Laser Rifle, Assault Laser and Heavy Laser.
** ''TabletopGame/RoleMaster'', ''Spacemaster Privateer'' campaign setting. Backpack energy cells can hold 35,000 energy units and are often used to power large weapons.
* [=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.
* ''StarFrontiers''. 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.
* R. Talsorian Games' ''[[TabletopGame/{{Cyberpunk}} Cyberpunk 2020]]''. The ''Pacific Rim Sourcebook'' had the [=MicroMortar=], a grenade launcher with its magazine of grenades stored in a backpack.
* ''TabletopGame/InNomine'': Belial, the Demon Prince of Fire, often appears wearing a flame thrower with a fuel tank backpack.
* ''TabletopGame/GammaWorld'': in 1st Edition, the fusion rifle was connected to a backpack that contained the atomic energy cell that powered it.
* ''Franchise/MenInBlack'' TabletopGame: the Plasma Rifle has a backpack power pack.
* ''Phoenix Command'': Battlepacks for PowerArmor infantry serve as an ammunition rack and reload system for the armor's weapon, such as 30mm grenade launchers.
* Fantasy Games Unlimited's ''TabletopGame/{{Aftermath}}!'' Book 3
** The U.S. Army XLMR-4 is a laser rifle that draws power from a backpack-type harness holding a powerful battery.
** Flamethrowers carry their napalm fuel in tanks held in a backpack harness.
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[[folder:Toys]]
* The Super Soaker [[http://www.isoaker.com/Armoury/Analysis/1998/super_soaker_cps3000.html CPS3000]] and [[http://www.isoaker.com/Armoury/Analysis/2000/super_soaker_cps3200.html CPS3200]] both feature backpack water reservoirs with significantly higher capacity than any other water gun out there.
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[[folder:Video Games]]
* The Ammunition Backpack in ''{{VideoGame/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.
** The Energy Pack in Tribes 1 and 2 simply increased the recharge rate of your energy bar, effectively increasing your energy weapon refire rate, but saw more use than the Ammo Pack due to the fact that it also allowed more jetpacking and also being required to equip the Laser Rifle.
* ''VideoGame/{{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 [[FrickinLaserBeams plasma rifle]].
* The minigun in ''VideoGame/ResidentEvil5'' 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.
* ''VideoGame/MetalGearSolid'': Vulcan Raven wears a massive ammo tank for his [[GatlingGood M61 Vulcan]] on his back.
** Flamethrower-wielding soldiers show up in ''VideoGame/MetalGearSolid3''. [[VideoGameCrueltyPotential Shooting their backpacks causes them to explode.]]
* Certain enemies in ''VideoGame/{{Borderlands}}'' have ammo tanks which can be blown up (which is good, since these enemies tend to be the insanely powerful ones).
* ''VideoGame/TeamFortress2'': The Medic has a backpack for his Medigun. Subverted slightly with Pyro; that thing on the Pyro's back is an oxygen tank, the ammunition is supplied by a propane canister on the flamethrowers itself (though the class selection screen [[OffModel still shows the backpack connected to the weapon]]). 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 ''TooHuman'' - some of the 'Troll' class enemies use heavy {{Grenade Launcher}}s, 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 [[DropTheHammer hammer-wielding]] brothers, but not because of their attack-range...
* ''VideoGame/{{Fallout 3}}'' and ''VideoGame/FalloutNewVegas'' features an ammo backpack for many [[{{BFG}} Big Guns]], like the minigun or flamethrower, as well as a motorcycle gas tank for a FlamingSword melee weapon. The Minigun has the ammo pack as well as motor, while the Gatling Laser has a huge battery pack. The Flamer has fuel tank, though strangely absent for the Incinerator.
* Flamer units in ''VideoGame/MassEffect2'' 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 [[LudicrousGibs 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.
* ''VideoGame/{{Portal 2}}'' showed one of the earliest models of the portal gun, it had a huge backpack used as energy storage.
* Jorge in ''VideoGame/HaloReach'' has one for his minigun. It doesn't slow him down one bit.
* A few of the heavy weapons in the ''VideoGame/BallisticWeapons'' mod for ''VideoGame/UnrealTournament2004'' are attached to backpacks of some sort. Flamethrowers and the like can have their backpacks damaged, causing the unlucky user to shoot into the air before exploding.
* ''VideoGame/CallOfDuty: World at War'' adds flamethrowers to the game. This being [[BloodierAndGorier World at War]], shooting enemies that are carrying flamethrowers, even if you don't hit the tank, often causes them to explode.
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[[folder:Web Comics]]
* ''Webcomic/{{SSDD}}'': "Black Rose" {{Plasma Cannon}}s are powered by a miniature fusion generator carried on the back. In fact they're one of the big weaknesses with the design, the connecting hose is fragile and if ruptured hot plasma spews out, and unlike larger reactors if magnetic containment is breached the plasma touches the casing for a split second before dissipating and superheats it, causing an explosion.
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[[folder:Western Animation]]
* Seeing as how the content of [[DoraTheExplorer Dora]]'s backpack changes to fit the need each episode, one imagines that this trope could take effect if Dora ever found herself [[WhatCouldHaveBeen running afoul of a drug cartel]].
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[[folder:Real Life]]
* Some [[FireBreathingWeapon 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) [[note]] Unlike Hollywood portrayals, an explosion won't happen from simply ''shooting'' the tank, however.[[/note]] 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 since been outlawed by the Geneva Convention.
*** However though people still use them anyway often claiming MundaneUtility. The most infamous case is how the US still uses phosphorus bombs for signaling, signals which conveniently also burn and poison the target. In terms of flamethrowers, they still use them to clear brush and Forrest lands, sometimes containing the enemy.
* The US Navy [=SEALs=] and MACVSOG had [[http://seahound1969.hp2.jp/wswu/Uthin/SEAL%20DMS%2001.JPG this]] during UsefulNotes/TheVietnamWar. In Panama, the Delta Force used [[http://img827.imageshack.us/img827/189/deltam249backpackairbor.jpg this]]. And in 2010, [[http://soldiersystems.net/blog1/wp-content/uploads/2010/09/MICO-Pack.jpg this]] [[http://www.everydaynodaysoff.com/wp-content/uploads/2010/09/Machine-Gunners-Assault-Pack-MICO.jpg backpack]] was unveiled.
* If you don't have the fancy stuff, you can easily macgyver one by emptying your backpack and duct-taping an ammo box or two to it. If you have a backpack with a frame, remove the sack entirely.
* Arguably, quivers for archers count, when not worn at the belt instead.
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