I have to say that I don't have statistics on all gun purchases. But there was a definite boom in one kind: old military guns, particularly rifles, which were obsolete at the end of WWII and a part of the giant Military Surplus supply, the huge deluge of war equipment in general. The back page of most American Rifleman magazines (and in many other gun magazines of the period) usually had an ad for a dozen or more different kinds, with prices hovering around $15-$25. Before 1968, these could be all mail-ordered. Surplus ammo was also sold cheaply. In other words, if gun sales boomed ( hah!) there may have been a fear-factor coming with the Cold War, but there would also have been a fire-sale aspect as well.