[Disturn]

perk [ playerid ] [ Ammo ] is set to 1. It's the only way your code isn't performing it's task.

pawn Код:

CMD:test(playerid, params[])
{
    perk[playerid][Ammo] = 0;
    return 1;
}

Call the command test before you refill.

EDIT: After you've tested to see that this is the issue (as obvious as it is), make changes to whatever is needed.