You have mastered a wide range of weapons. Your training with one specific weapon now extends to other weapons of a similar sort.
Prerequisites: Proficiency, Weapon Focus, and Weapon Specialization with selected weapon; base attack bonus +8.
Benefit: When you select this feat, choose bludgeoning, piercing, or slashing. You must have Weapon Focus and Weapon Specialization with a ranged weapon that deals this type of damage. When using any ranged weapon that has the damage type you selected, you gain a +2 bonus on attacks and a +2 bonus on damage. In addition, you increase its range increment by 20 feet. The bonuses from this feat do stack with those gained from Weapon Focus and Weapon Specialization.
Special: You can select this feat more than once. Each time, you can select a new damage type.
A fighter can select Ranged Weapon Mastery as one of his fighter bonus feats.
Source: Player’s Handbook II, page 82.