Ammo racks
Contents
General
Each ground and naval vehicle has its ammunition stored in a series of racks. Each vehicle has its individual rack configuration and each rack carries a specific number of shells. These racks can be seen in-game with X-Ray viewing mode (be sure to bind a key to 'Common > Basic > X-ray (show vehicle modules)').
Rack types
Single piece ammunition Most tanks use single piece ammunition where projectiles and propellants are in one piece.
Two piece ammunition Some high calibre cannons have two piece ammunition where projectiles and propellants are stored and loaded separately. Each piece has their own individual racks. These racks can be depleted synchronously (for example in the Jagdtiger) or deplete independently of one another (for example in the M103).
Magazines and ammo boxes Vehicles with automatic cannon(s) often have their ammunition stored in magazines, clips, belts and/or ammo boxes. In the loadout screen, ammunition amount is selected in magazines. For example, the Ostwind can load up to 125 magazines instead of 1000 shells.
Multi turret and multi cannon Multi-turreted and multi-cannon vehicles (for example T-35 or M6A1 or most naval vessels) have individual racks for each ammo type. Tanks like the Maus could also have three kinds of racks, 12.8 cm projectiles, 12.8 cm propellants and 7.5 cm shells.
Twin and Quad cannons Some SPAAs have twin and quad mounts for their main armament. Each of these cannons gets loaded separately. Since all of its guns are firing in more or less a synchronized manner, it may look like the cannon are loaded as one. For example, the M13 MGMC holds 2 x 200 rounds in its two machine guns, while the game shows it as 400 rounds loaded.
Depth charges A single-piece ammunition released overboard, upon destruction it has a chance of exploding, much like other ammunition types.
Torpedoes While being a relatively large target onboard most of the vessels, torpedoes have comparatively low chance of explosion upon destruction.
Rack depletion
Racks vanish once all shells in that rack are depleted. Some vehicles have their shells modeled individually, meaning that the shells disappear from the rack as they are fired, while others may have racks modeled as a whole (for example, a rack containing 6 shells only vanishes once all of its six shells are depleted). However, see "Visual Discrepancy" below. The order in which the racks are filled and depleted does not change no matter how many shells are available (the exception being first-stage ammo racks, which will always deplete first if available, and will refill from the other ammo racks after an extended break in firing). A depleted rack or vanished shell cannot cause an ammo rack detonation, so care should be taken in choosing the number of shells to equip into battle to maximise the survivability of the vehicle (see #Optimized ammo rack loadout).
Shell types
Ammo racks are shared for all shell types loaded. It doesn't matter which shells are used first, the racks will always deplete in a given order (assuming the ammunition is all fired from one cannon).
Visual discrepancy
Some vehicles may carry a different number of shells in its racks than are visibly modeled in the X-Ray view. This is known as "Visual discrepancy", and can occur in both a vehicle as a whole (eg a vehicle visually contains 80 shells but in fact only carries 60 when fully equipped) or in individual racks (eg a rack looks to contain 5 shells but 8 must be fired for it to deplete). These cases should be reported via the appropriate bug-reporting channels on the Official War Thunder Forums. Note that racks being modeled as a whole instead of individually is NOT visual discrepancy, and should not be reported or marked as such.
Optimized ammo rack loadout
The fastest way to get destroyed in tank battles is by detonation of the ammunition. Therefore, a good way to increase survivability is to reduce the number of shells loaded on the tank. Survivability is greatly reduced while shells are stored in bundles, distributed all around the tank in different locations. These racks can be seen with x-ray view, and are consumed while firing, rack-by-rack or shell-by-shell depending on the vehicle. Once a rack/shell is depleted, it cannot explode anymore, thereby decreasing the chance of getting 'ammo racked'.
Being 'ammo racked' is the situation in which a group of ammunition takes damage from enemy fire (gets shot by another tank) and causes the explosive mass in the ammunition to detonate. Any time ammunition inside the tank is detonated, it causes catastrophic damage to the tank.
Each tank has a different ammo rack setup and therefore, there is no universal rule on how much a lower ammo count increases survivability. Ammo racks in the turret are much more susceptible to being shot, but there is no guarantee that the ammo rack in the turret is the first to be expended.
Loadout screen
The loadout screen shows the number of unloaded shells in brackets. The number remaining to be loaded are a total of the maximum available, and not per shell type.
Use this to gauge how much ammunition and how much of each type to bring when considering the number of ammo racks filled and survivability. Loading too little shells may result in you running out of ammunition in the heat of battle, while cramming as many shells in as possible increases the chance of an ammo explosion. Ammunition can be reloaded at any capture zone controlled by your team.