3e SRD:Masterwork Weapons
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These well-made weapons add a +1 bonus to attack rolls. A masterwork weapon's bonus to attack does not stack with an enhancement bonus to attack.
Masterwork Arrow, Bolt, or Bullet
A masterwork projectile functions like a normal projectile of the same type except that it is so aerodynamically sound that a +1 bonus on attack rolls is added when using it. This bonus stacks with any bonus a character might get by using a masterwork bow, crossbow, or sling. The projectile is damaged (effectively destroyed) when it is used.