Last month, 51,772 purchases were approved, according to the Colorado Bureau of Investigation's background check system. That's a 64 percent jump over November. Background checks are required for public and private transactions in Colorado.
That makes December 2015 the third-biggest month for gun sales, trailing only December 2012 and January 2013 for the top spot. Each time sales spiked following mass shootings and calls for new gun control measures.
For the year, 2015 is now the second-best year for gun sellers, with CBI approving 342,839 purchases. The record year was 2013, with 389,604 background check approvals.