Manage ammunition and the ready rack
Carry enough ammunition to finish useful fights without filling storage you do not need. The right load depends on the vehicle's rack layout, your firing rate and the route back to resupply. Neither maximum capacity nor an arbitrary twenty-round rule answers all three.
Separate storage from the round in the gun
Total capacity, first-stage storage and the round already chambered are different counts. A vehicle can have ammunition remaining while its fastest-access rack is empty. It can also show a loadout count that does not match a simple rack-capacity-plus-one assumption.
Inspect the exact vehicle with the spawn load you intend to use. Check the in-battle X-ray rather than relying on the hangar's full ammunition display. Note which racks are occupied at that load and where the rounds sit relative to the crew and common incoming shot paths.
Reduce exposed storage for a reason
Removing unnecessary rounds can empty vulnerable racks, but taking one fewer shell does not necessarily empty the particular rack you want. The vehicle's loading order decides that. Reduce the load, verify the resulting storage, then choose a total you can actually fight with.
Less ammunition does not remove the risk of a crew kill or make the remaining rack safe. If the first-stage rack is inside the fighting compartment, keeping only that rack loaded still leaves ammunition near the crew. Positioning remains the first protection.
Budget all shell types together
Your main round, HE and specialist ammunition share the vehicle's total load. Adding a handful of each alternative can refill storage you deliberately emptied. Count the complete loadout, not just the number beside your preferred shell.
For an ammunition-hungry vehicle holding a long crossing, a little more endurance may be worth the extra storage. For a short opening followed by a covered resupply route, the same reserve may add risk without being used. Base the decision on the engagements you are planning, then adjust from actual consumption.
Leave before the fast rack runs dry
The 75 mm AMX-13 lists a 12-round first-order supply and a five-second autoloader cycle. That is a useful burst of fire, not a promise of five-second shots for the entire ammunition load. Check the displayed ready supply and chamber state rather than turning those figures into an assumed universal spawn count.
A short reload while the first-stage rack is stocked is not evidence that you can maintain that pace indefinitely. Watch the ready supply during repeated shots. When it is nearly empty, decide whether to finish the current fight or disengage before starting another one.
For example, you have enough ready rounds to deal with the tank already exposed, but another enemy is waiting behind it. Spending the last quick shot on a poor angle can leave you unable to answer the second tank. Withdraw while the first enemy still has to cross your teammate's gun, rather than discovering the longer reload in the open.
Understand what your loader can and cannot do
Manual loading, replenishment of a first-stage rack and an autoloader's mechanical cycle are separate processes. Crew improvements do not shorten the mechanical loading cycle of an autoloader. A damaged autoloader can prevent further loading even when ammunition remains; a round already in the gun can still be a threat.
Learn the exact vehicle's replenishment behavior in a safe environment. Observe the relevant indicators while firing and while waiting under cover. Do not assume that every drum, carousel or manually loaded ready rack replenishes at the same rate or under the same conditions.
Resupply without giving away the tank
Returning to a friendly capture point is useful only if the approach and stopping position are defensible. Check the lanes into it before committing. A nearly empty tank should not lead a push that requires several shots before reaching cover.
If the objective is under fire, cover a teammate or change lanes until a workable resupply route opens. A conservative load has become too small when it repeatedly forces you to abandon the decisive part of the match. Increase it deliberately and recheck which storage that fills.