Ammunition: Projectile weapons use ammunition: arrows (for bows), bolts (for crossbows), or sling bullets (for slings).
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Projectile Weapons: Light crossbows, slings, heavy crossbows, shortbows, composite shortbows, longbows, composite longbows, hand crossbows, and repeating crossbows are projectile weapons.
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Although they are thrown weapons, shuriken are treated as ammunition for the purposes of drawing them, crafting masterwork or otherwise special versions of them and what happens to them after they are thrown.