School shooter Karl Pierson purchased an as-yet-unidentified 12-gauge pump action shotgun at an as-yet-unidentified Denver-area gun store on Dec. 6, and bought ammunition Thursday, Arapahoe County Sheriff Grayson Robinson told the media. Pierson turned 18 on Sept. 3, making the purchase legal. Colorado gun law does not require a permit to purchase a rifle or shotgun. The gun does not have to be registered with the state. There is no indication that the attack will spur changes in the law. Yet.
(Post was updated to remove an erroneous statement that a background check was not required.)