how about this, I think it should work
$DamageType::ShotgunProjectile= 24;
addDamageType($DamageType::ShotgunProjectile, "Shotgun");
addDeathMessage(Kill, $DamageType::ShotgunProjectile, '~g%1 was pulped by %2');
and you need to change in the code above, this
damageType =...