There is no precise data on U.S. gun sales but the FBI file repository provides a good estimate through the number of background checks that it performs from the National Instant Criminal Background Check System (NICS). The NICS requires gun sellers to run the names of potential gun buyers to ensure they aren't disqualified from buying a firearm.

There are gun sales that aren't subject to background checks, so those gun purchases go uncounted.

The NICS statistics show there were 25,235,215 background checks in 2017, and as of October, there have been 21,245,508 background checks in 2018.

Since 1998, there have been more than 230 million background checks, leading to more than 1.3 million denials.

According to industry research group IBISWorld, gun sales had hit a record high of $9 billion in 2016, a 3.6 percent gain from 2015. The Gun & Ammunition Stores industry over the past five years has grown by 3.8 percent to reach total revenue of $11 billion in 2018.

Reports have suggested a slowdown in gun sales since Donald Trump was elected president in November 2016. Gun sales tend to surge when there is fear of potential regulations, which was the case during the Obama administration.

Gun production has climbed from 3 million in 1986 to 9 million in 2015, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Gun Shop Near Ferguson Sees Increase In Business Ahead Of Awaited Grand Jury Decision BRIDGETON, MO - NOVEMBER 12: Customers shop for a handgun at Metro Shooting Supplies on November 12, 2014 in Bridgeton, Missouri. The suburban St. Louis store is located near Ferguson, Missouri where several weeks of sometimes violent protests erupted following the shooting death of Michael Brown by Ferguson police officer Darren Wilson on August 9th. The gun shop last week experienced a 300 percent increase in sales over the same period last year. About 60 percent of those sales were from first-time gun owners. The increase is attributed in part to concern from residents of additional outbreaks of violence if the grand jury investigating Brown's death does not find justification to prosecute Wilson for the shooting. The grand jurys decision is expected sometime in November. (Photo by Scott Olson/Getty Images)2 Scott Olson / Staff