Actually, it's all concealed carry weapon (CCW) permit holders in Missouri - not all gun owners - since CCW is the only registration of gun owners kept on file by the states.
But why do the Feds need with this info? Or, more specifically, what does the Social Security Administration Office of Inspector General need with this info?? And why did the Missouri State Highway Patrol - which is directly answerable to Gov. Jay Nixon (a democrat) - supply that info to the Feds??
BTW: Anyone attempting to purchase a firearm via a federal firearms license (FFL) dealer is ran through the FBI NICS (National Instant Criminal Background Check System), but those records are destroyed soon after the check is complete.