Magical companion ammo is a special ammunition type that companions with ranged weaponry use when no regular ammunition is currently within their inventory. Magical companion ammo is infinite (unless certain conditions are met) and hidden. e.g. Craig Boone has an endless amount of .308 rounds for his hunting rifle, and as there is only his clothing in his inventory, the magical companion ammo is hidden. Otherwise, one could legitimately obtain infinite ammunition.
Leaving a companion without any of their magical companion ammo will mean that they will be unable to fire their ranged weapon until proper ammunition is returned.
If using this ammunition for Lily's assault carbine, the ammunition will not be unlimited. It will be fired much like regular ammunition.
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