Gun sales bang on Black Friday: FBI performs over 144,000 background checks as Thanksgiving shoppers stock up on firearms (that's 120 per minute)

• There were 144,758 background checks done last year
• Over 94,000 had been processed by 2pm Friday
• FBI brings in 100 extra employees to help process the checks
• They have three days to complete a check or the buyer can get a gun without needing one
• More than 186,000 background checks were not completed on time in 2013

By Joel Christie for The Mailonline

Published: 23:00 EST, 28 November 2014 | Updated: 01:55 EST, 29 November 2014

The Federal Bureau of Investigation says it does not have enough staff to calculate the thousands of background checks required by law when buying a firearm, as gun sales are expected to hit a record amount from Black Friday.

The busiest shopping day of the year is expected to yield more 144,000 checks and is on track to surpass last year's record 144,758, CNN reported.

'We are averaging three checks per second,' FBI spokesman Stephen Fischer told the network.

'The challenge is to have staff keep up with this volume.'

Boom: There have been 120 background checks per minute for Black Friday gun sales this year

The FBI runs the checks from a call center, which has about 600 staff.

An extra 100 employees are brought in for the Black Friday rush.

Many employees have been asked to pick up extra shifts and are pulling 17-hour shifts in an attempt to get on top of the work.

The agency has only three business days to complete the checks.

Failing to do so means the person trying to buy the gun is allowed to purchase the weapon without being checked out at the discretion of the vendor.

Most major retailers will not allow a purchase to go through without a completed check.

Required by law: The FBI has brought in an additional 100 people to do background checks during Black Friday and they will be working extended hours to try and keep up with demands

Background check: The FBI's National Instant Criminal Background Check System said over 500 checks each day fail because of incomplete information

Last year, more than 186,000 background checks were not completed on time.

That is out of the 21 million background checks that were completed on time.

The agency typically processes about 58,000 checks a day.

About 500 of that number fail due to incomplete information.

According to CNN, about 3,000 - or 2 percent - of the more than 144,000 Black Friday background checks will not be completed because of insufficient information.

More than 94,000 checks had been processed by 2pm Friday.

When the FBI introduced their background check system in 1999, there were only about nine million checks a year.

Busy time: Metro Shooting Supplies' employee Chris Cox (left) speaks to Steve Christy about the purchase of a 9mm handgun in Bridgeton, Missouri on November 13, 2014

There are 10 factors that could cause a gun purchase to be denied, according to CNN.

- Felony conviction

- Arrest warrant

- Documented drug problem

- Mental illness

- Undocumented immigration status

- Dishonorable military discharge

- Renunciation of U.S. citizenship

- Restraining order,

- History of domestic violence

- Indictment for any crime punishable by longer than one year of prison.

The FBI cannot deny a gun purchase based on an arrest.

They first have to investigate the crime.