Firearm Sniper (3.5e Feat)
From D&D Wiki
Firearm Sniper [General]
You are adept in lining up accurate, deadly shots with your gun.
Prerequisite: Proficiency with at least one firearm, Weapon Focus (any firearm), base attack bonus +1
Benefit: Upon gaining this feat, you may apply 1/2 your Dexterity bonus to damage rolls made with any firearm that you have Weapon Focus with. If you have the sneak attack, sudden strike, or skirmish ability, the maximum range that you may use those abilities is extended by 60 feet if you are using a firearm that you have Weapon Focus with.
Special: A fighter may select firearm sniper for one of his bonus feats. Note: This is the feat Crossbow Sniper, which is from the Player's Handbook II page 77, adapted for firearms.