Charlton Heston would have accidentally shot someone during an NRA rally, people would be saying to always assume a gun is loaded.
Its a mantra that is very real with gun and shooting enthusiasts. When my son started shooting pellet guns, I must have repeated the basics of gun safety so often that it drove him up the wall. "I know . . . I KNOW!!!" he'd tell me while unintentionally swinging the muzzle of the pellet gun in an unsafe direction, and watching me come (mildly) unglued.
But when we've gone to play paintball or have shot rimfire rifles with his younger siblings and cousins, he becomes the AUTHORITY on gun safety and reminds everyone to assume the gun is loaded, to keep the muzzle pointed in a safe direction, etc. It sticks in your head.
So we'd still be hearing it on CB.