m4_dmg = getWeaponProperty(31,'pro','damage')

addEventHandler('onClientPlayerDamage',localPlayer,function(asesino,arma)
    if asesino and isElement(asesino) and asesino ~= source then
        if arma == 31 then
            local dmg = getElementData(asesino,'m4_dmg') or 0
            local vida = getElementHealth(source)
            setElementHealth(source,vida-dmg)
            cancelEvent()
        end
    end
end)