TTAG has learned that spree killer Adam Lanza fired his mother’s Bushmaster AR-15 79 times inside the Sandy Hook Elementary school before experiencing a stovepipe. (An empty, fired cartridge failed to eject from the rifle and became stuck in the action, preventing another cartridge from firing.) Lanza did not clear the weapon. Investigators found the non-functional AR-15 at least five feet away from the killer’s body; he may have thrown the rifle after the malfunction before switching to a handgun. A source close to the investigation says Lanza killed himself within seconds of making eye contact with one of the first responders.