The Colorado Bureau of Investigation reported it was on track to perform 4,000 background checks Friday on people purchasing firearms.
In 2011, CBI's InstaCheck unit set a single-day record by checking 3,031 gun buyers.
The CBI checks gun buyers against a mix of seven state and federal databases for criminal records, a process that takes less than four minutes on average.
The sheer number of checks around the holidays creates a backlog for the office, which has about 30 workers on staff.
"We plan for months leading up to this," CBI spokesperson Susan Medina said. "There's no vacation. We stagger our starts. We have everybody here so that we maximize efficiency so that we make this process go as quickly as possible."
Friday morning, background checks took three to four hours to turn around. The CBI doesn't track reasons why gun sales are increasing.
The demand came from people like Rick Russolello, who lined up at 4 a.m. outside of Bass Pro Shop in Stapleton to buy a gun for the first time.
Testing the pump action on his new black 12-gauge shotgun, his motivation sounded similar to any other Black Friday shopper.
"The doors opened at five, so I stood in line for an hour in the cold," Russolello said. "I was in here ready to go and knew what gun I wanted to get because there was a nice deal on it."
He killed time by watching a movie and grabbing lunch while waiting for his background check.
Next time he gets a day off, he'll be up early again - this time to go shoot clay pigeons.