2015 was a record year for background checks for guns in the United States according to FBI data posted Monday, there were 23,141,970 background checks in 2015. This beats the prior record of 21,093,273 in 2013.
This means that last year was probably a record year for gun sales. FBI background checks are conducted for all gun sales that go through a federally licensed dealer, which is how the majority of guns are sold. So background checks serve as an proxy for gun sales, though not a precise measure.
The sales were driven by a series of mass shootings that typically motivate buyers who fear more restrictive gun control measures.

Shootings also make people feel unsafe, so they buy guns for self-protection. The shooting in San Bernardino is a good example of this. These shooting Mass shootings, like the one in San Bernardino, Calif., helped to drive gun sales, which lead to a record year for background checks in 2016.
December was the biggest month ever, with 3,314,594 checks. It was the first month to surpass 3 million since the FBI started tracking background checks in 1998. It’s also the month that two terrorists fatally shot 14 people in San Bernardino. Since it was the holidays and the victims were just innocently attending a holiday function, it puts people on high alert because in all reality the victims were doing something we all do.
Prior to that, the record month was December 2012, when a gunman killed 20 children and six adults at Sandy Hook Elementary School in Newtown. The shooting prompted a strong push for gun control by President Obama and congressional Democrats.

It will be interesting to see what the new open carry gun law in Texas does for gun sales also.