Scott A. Biumi, 48, of Cumming, was arrested and charged with aggravated assault for the April 4 incident, The Atlanta Journal-Constitution reported.
Police said Biumi was in his car in the McDonald's drive-through when he became upset with another customer.
"He exited his car, and following a verbal exchange with the customer, Biumi drew a gun and pointed it at the victim," Deputy Courtney Spriggs with the Forsyth sheriff's office said in a statement.
Surveillance video footage from McDonald's shows a man, identified as Biumi, get out of his vehicle and allegedly lunge into a pickup truck in front of his vehicle and grab teenage victim Ryan Mash.
Mash told Channel 2 Action News that Biumi was upset because he was taking too long to place his order.
"He grabbed me on my right shoulder and pinned me against my driver's seat, and the next thing I know, I have a gun in my face," Mash told Channel 2. "He goes, 'Do you know who you're messing with,' and 'You shouldn't be holding up the line' and all this and that."
Biumi, who was employed as a detective sergeant with DeKalb police, is scheduled to appear in court for the incident on May 23. He was bonded out of jail on Wednesday.