Crack Shot (D20 Modern Feat)
From D&D Wiki
When wielding a lasgun or other handheld firearm (such as a slugthrower or maula pistol), you are considered “armed.” You threaten your adjacent areas and can thus make attacks of opportunity against those who leave them.
Prerequisite: BAB 1+, Two-Weapon Fighting.
Benefit: You threaten a 2-meter area around you in any direction with a pistol, just as with a melee weapon.