You can Ritual Summon this card with "Ammunition Ritual". If this card is Ritual Summoned: You can target 1 Level 4 or lower DARK Dragon monster in your GY; add it to your hand. You can only use this effect of "Barrel Chamber Dragon" once per turn. If this card battles an opponent's monster, any battle damage this card inflicts to your opponent is doubled. (Quick Effect): You can target 1 other Dragon monster you control and 1 card your opponent controls; change the first target's battle position, and if you do, destroy the second target. You can only use this effect of "Barrel Chamber Dragon" once per turn.