The function BIS_fnc_saveInventory does not save the magazines ammo count.
And the associated function BIS_fnc_loadInventory does not set the magazines ammo count.
Currently, we have no easy BIS' function/command to duplicate accurately a unit loadout.
Fire somme ammo from one on several player's magazines.
Execute this code in the debug console :
0 spawn
{
sleep 4;
[
player,
[player] call BIS_fnc_saveInventory
] call BIS_fnc_loadInventory;};
After the save&load of loadout, the player has all its magazines fully filled.