Lots of guns
There's no limit to how many weapons you can carry, which makes for some ridiculous scenes. Bethesda

In 2013 there were 365 mass shootings in the U.S., with mass shootings defined as incidents where four or more people are injured or killed. Since the tragic December 2012 killing of students and teachers at Sandy Hook Elementary School in Newtown, Connecticut, there have been 74 more school shootings. And with each highly publicized incident, gun sales have spiked, as people become concerned about their own safety and about potential new gun control measures restricting their ownership or use of guns.

Typically after a shooting, politicians and the media are quick to comment on gun control, discussing whether current laws are adequate or change is needed. When President Barack Obama issued executive actions after Sandy Hook, more than 60 percent of Newtown news stories included a reference to gun control. When more gun control seems possible or imminent, gun rights activists concerned about increasing regulations anxiously stock up on guns and ammunition.

This is all good news for Smith & Wesson Holding Corp. (NASDAQ:SWHC), one of the nation’s largest gun makers, which recently reported record sales in its latest fiscal year.

According to the FBI, the top 10 busiest days for firearm background checks have all occurred since the Newtown killings.

gun sales and shootings
International Business Times/Hanna Sender International Business Times/Hanna Sender
The FBI's numbers represent the "number of firearm background checks initiated through the NICS [and not] the number of firearms sold." Since gun sales figures are not systematically reported or regulated, the number of background checks, while not a direct correlation, is considered a good indicator of sales.
See the full list of 2013 and 2014 mass shootings here.