Although they've been overshadowed a bit by handgun buyers in recent years, public data suggest that hunters are the backbone of U.S. firearms sales. According IBISWorld, American civilians purchase roughly $7 billion worth of guns and ammunition annually. And although their analysis doesn't separate money spent by sportsmen from purchases by doomsday preppers, the U.S. Fish and Wildlife Service estimates that hunters alone alone spent around $4.3 billion on guns and ammo in 2011.

In short, when we talk about hunting, we're talking about a pastime responsible for more than half of retail gun sales. And over the past 20 years, hunting has not fared well. Although their numbers have risen since hitting a trough in 2006, there are around 300,000 fewer Americans stalking deer, cramming themselves into duck blinds, and gunning down turkeys than in 1991, according to the Fish and Wildlife Service. As a result, hunters have fallen from more than 7 percent of the population to a bit under 6 percent.

But sheer numbers aren't the only problem. Simply put, America's hunters are getting old. In 1991, 71 percent were under the age of 45; today less than half are. It's a stagnant population that's been graying for years, and soon, old age and shrinking, post-retirement incomes will force many to give up their hobby. As a result, gun makers are staring down a demographic and financial disaster.

Unless, that is, young people start shooting game again. And here, there's actually some happy news for the industry. Right now there are modest signs of a youth revival in hunting. According the Fish and Wildlife Service, the number of 6-to-15-year-olds who hunted increased by about 14 percent from 2005 to 2010, a bit faster than the rate of growth in the adult hunting population. Are assault rifles for 'tweens and junior-shooter programs to thank? Who can say. But at the very least, their efforts don't seem to be hurting business -- no matter how horrifying some parents might find them.