RIGHT SPEAK: Black Friday Gun Sales resulted in a Record Breaking of almost 3 Background Checks Per-Second

The busiest shopping day of the year also saw a major boom for gun sales, with the federal background check system setting a record of more than 175,000 background checks Friday, according to the FBI.

The staggering number of checks -- an average of almost three per second, nearly three times the daily average -- falls on the shoulders of 600 FBI and contract call center employees who will endure 17-hour workdays in an attempt to complete the background reviews in three business days, as required by law, FBI spokesman Stephen Fischer said.

"Traditionally, Black Friday is one of our busiest days for transaction volume," Fischer said.

Indeed, Friday saw the highest number of background checks ever for a Black Friday, and second in history. The highest day on record was December 21, 2012, with more than 177,000 background checks.

On average, more than 500 gun background checks a day fail because of incomplete information required for a decision, according to the FBI's National Instant Criminal Background Check System, which is responsible for checks on firearm purchases from federally licensed shops.

Employees of the background check agency, who work every day but Christmas, worked through the weekend to vet Friday's purchases.

"We are averaging three checks per second," Fischer said Friday afternoon, before the final numbers were in. "The challenge is to have staff keep up with this volume. We do that by limiting personal leave, asking employees to work extra shifts and reutilizing former ... employees to serve in NICS during this busy period."