Function SetPlayerAmmo set the ammo of a player's weapon.
The param 'weaponslot' is a typo in the sa-mp include. You must use the weapon ID and not the weapon slot of the weapon you would like to set the ammo of.
Set the ammo to 0 to remove a weapon from a player's inventory. Note that the weapon will still show up in GetPlayerWeaponData, albeit with 0 ammo.

(playerid, weaponid, ammo)
int playerid The ID of the player to set the weapon ammo of.
int weaponid The ID of the weapon to set the ammo of. (not the weaponslot as in samp include)
int ammo The amount of ammo to set.

Return Values:
  • 1: The function was executed successfully. Success is also returned when the weapon slot specified is invalid (not 0-12).
  • 0: The function failed to execute. The player isn't connected.

SetPlayerAmmo(playerid, WEAPON_SHOTGUN, 100); // Set ammo of Shotgun to 100 bullets

Related Functions
The following functions may be useful, as they are related to this function in one way or another.