By Jackie Wattles

NEW YORK (CNNMoney) -- Americans are buying guns in record numbers. And if history is any guide, Sunday's mass shooting in Orlando will spur even more firearm sales.

According to FBI data, 2016 is on pace to set the record for the most firearm background checks in a year.

The FBI conducts a check for every gun purchase made through a federally licensed dealer, so background checks are considered a close proxy for gun sales. Not all guns are sold by federally licensed dealers, and a single background check can represent the purchase of multiple guns.

About 23.1 million checks were conducted in 2015 -- the highest ever recorded since the current system for background checks was started in 1998. This year, 11.7 million checks have been conducted through May 31, compared to 8.9 million over the same period last year.

The purpose of the checks is to screen potential buyers for felony convictions, mental illness, history of domestic violence and drug abuse.

In recent years, news of mass shootings have often led to a spike in gun sales, as fears about personal safety grow and some gun buyers worry that regulatory crackdowns would make it harder to purchase weapons.

Not surprisingly, business is good for the largest gun manufacturers.

Smith & Wesson reported in March that the company's quarterly net sales rose 61.5% compared to the same period last year. And analysts expect annual sales at Smith & Wesson and Sturm Ruger to grow by about 30% each this year compared to 2015.

In the wake of more frequent and more deadly mass shootings, President Obama has announced executive actions aimed at tamping down gun access.

Several states have also passed measures to bolster background checks or ban assault weapons or high-capacity magazines.

Few details were immediately known Sunday about the weapons used by the Orlando gunman, Omar Mateen of Ft. Pierce, Florida. Mateen legally purchased a handgun and a long gun within the last few days, ATF Assistant Special Agent in Charge Trevor Velinor said. "He is not a prohibited person," he added.

Mateen, 29, shot more than 100 people, killing an estimated 50 of them. Officials say he pledged loyalty to ISIS shortly after the shooting. It was the worst terror attack in the United Since since 9/11 and the deadliest mass shooting in the country's history.

Florida does not ban assault weapons or high-capacity magazines.

-- CNNMoney's Aaron Smith contributed to this report.

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