Marked Bullets are consumable items that add an extra attack die with 100% hit rate in combat. Up to 3 bullets can be added to the player's turn in battle, and can be used in combos normally. Marked bullets do not require a gun to be used.
These are primarily obtained with the Bullet Hoarder perk, which causes the explorer to find a single bullet every ~20 days. A rare event can also occur in which a British Soldier or Scottish Soldier companion with max Loyalty can present found Marked Bullets to the player as a gift.