The Obama years have been a boon to U.S. gun manufacturers. Bolstered in part by fears of new gun restrictions, American firearm companies roughly doubled their annual output between 2009 and 2013.

But new numbers released this month from the Bureau of Alcohol, Tobacco and Firearms suggest that that gun wave has crested -- at least for now. In 2014, the latest year for which complete data are available, gun manufacturers made 1.4 million fewer guns than they did the year before. That's the biggest year-over-year drop, percentage-wise, since 2001.

"What goes up must come down," said Gary Kleck, a criminologist who studies guns at Florida State University. The number for 2014 "represents a big drop from 2013, but that's only because the 2013 [figure] was so incredibly high," Kleck said. "By historical standards, the 2014 total is still huge -- just not as huge as 2013's figure."

Kleck attributes the big run-up in gun sales in recent years to an "Obama effect" -- "people (unrealistically) anticipating that the Obama administration would implement strict gun controls, such as a renewed assault weapons ban, raced out and bought up every gun they thought might get banned," he said.

Those strict controls never materialized. President Obama settled, earlier this year, for a fundamentally modest package of executive orders, including changes that many gun advocates have been clamoring for, like an increased focus on mental health and better enforcement of existing laws.

"The end of the Obama administration was in sight by 2014," Kleck said, "and it had not implemented any significant new gun controls in its first five years, and this may have cut into the panic buying evident in the 2009-2013 period."

Philip Cook, a Duke University gun policy expert, thinks that the gun market may be correcting after years of ramped-up production. "The surge in manufacture and import during 2013 was an attempt to keep up with the surge in demand following the Sandy Hook massacre," he said. "Quite possibly it overshot the mark a bit."

It's possible, Kleck added, that "just about everyone who wanted a gun, or more guns, got them in the immediately preceding years, leaving fewer people with unsatisfied desires for a gun [in 2014]."

But Cook notes that a renewed interest in the national gun control debate in 2015, following a string of high-profile mass shootings, may have lead to a rebound in gun manufacturing last year. "Looking to the future, I would bet heavily that manufacturing and import for 2015 will prove to be higher than for 2014," he said.

Cook notes that federal background checks processed when people purchase a gun were up 10 percent in 2015. "That squares with everything we’ve heard about 2015, a year when discussions of firearms regulation were much in the news under the leadership of President Obama."

The big-picture story, both Cook and Kleck agree, is the huge surge in firearm manufacturing during the Obama years overall. According to Kleck's latest estimates, there were 370 million civilian firearms in circulation in 2014 -- nearly 1.2 guns for every man, woman and child.