After hitting an all-time high of 2.8 million in December 2012, checks run through the FBI’s National Instant Criminal Background Check System remained high through May when compared to previous year tallies. Sales then dropped for the next four months, though October saw a slight increase compared to October 2012, according to the latest numbers.

“I know there was a period after Newtown when you couldn’t go into a Wal-Mart and not be able to find an AR-15 variant,” said David Chipman, a former agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives. “People are opportunistic buyers — they bought them because they thought they were going to be banned.”

The federal background checks are not a one-to-one correlation to gun sales; for example, some of the checks are performed on active concealed carry permits, among other nonsale actions. But despite such imperfections, the number of checks performed is widely considered a fairly good proxy for the number of guns sold.