By now, you can set your watch to a phenomenon that follows nearly every mass shooting in America: A sharp uptick in gun sales. It happened after the shootings at Virginia Tech, it happened after Columbine and Tucson, and it's happening now following the theater shootings in Aurora, Colorado, The Denver Post's Sara Burnett reports. "Background checks for people wanting to buy guns in Colorado jumped more than 41 percent after Friday morning's shooting at an Aurora movie theater, and firearms instructors say they're also seeing increased interest in the training required for a concealed-carry permit," Burnett wrote. Considering that massacres like Colorado's, which resulted in 12 deaths and 58 injuries, typically provoke sentiment about restricting, not proliferating guns, it's always a little incongruous to hear about these gun-buying bonanzas. But does the former sentiment drive the latter, or is another factor at play? Here are the top reasons for a post-massacre gun surge:

The desire to protect one's self In many cases, gun shootings followed by 24/7 media coverage prompt citizens to arm themselves, according to testimonies. In Aurora, for instance, Jake Meyers of Rocky Mountain Guns and Ammo told The Post shoppers cited self-protection when checking out new weapons. "A lot of it is people saying, 'I didn't think I needed a gun, but now I do,' " Meyers said. "When it happens in your backyard, people start reassessing — 'Hey, I go to the movies.'"

The fear of stricter gun laws Another logical factor is that gun owners' or soon-to-be-gun owners' sense a tide of gun control regulations following a massacre and seek to purchase guns ahead of fast-moving laws. Paul Helmke, president of the Brady Campaign to Prevent Gun Violence, spoke to this following a 60 percent uptick in gun sales in the aftermath of the Tucson shootings in 2011. "Some Americans fear tougher gun control laws in the aftermath of Saturday’s attack so they want to stock up now," he told Politico. “What it shows is maybe gun owners in Arizona and these other states feel that there’s going to be some change in the law, which is what I hope our elected officials” trying to enact. Obviously, that fear has been unfounded. Since coming into office, Obama has been virtually silent on the issue of gun control, despite the protestations of liberals.

The feeling of uncertainty It's important to remember, spikes in guns sales don't just coincide with shooting sprees. They also coincide with violent events of any kind, as Fredrick Kunkle at The Washington Post reported. "People also rushed to buy guns after the 1992 riots in Los Angeles and the breakdown of order in New Orleans after Hurricane Katrina." That has led some industry experts and law enforcement officials to point to a general feeling of uncertainty as a driver of gun buying habits. "People often buy firearms during periods of uncertainty," Gary Kleck, a researcher at Florida State University's College of Criminology and Criminal Justice, told the paper.

A Democrat is about to win an election There's also something to be said of the combination of a gun massacre happening against the backdrop of an election where many suspect a Democrat, in this case President Obama, will win. "It's definitely the election year," former CIA agent Jason Hanson told Fox News earlier in March. "People feel that Obama will serve second term and with it their gun rights with taken away, so they are stocking up." However, that's a phenomenon that doesn't actually require a massacre, given that in 2008, gun sales also skyrocketed.