Which of the following is NOT one of the four primary rules of firearm safety?

The four primary rules of firearm safety are designed to ensure the safe handling and use of firearms to minimize the risk of accidents. Keeping your finger outside the trigger guard until you are ready to shoot is fundamental to preventing unintentional discharges. Being sure of your target and what lies beyond it ensures that you are aware of your entire surroundings before you shoot, preventing harm to others. Treating every firearm as if it were loaded is crucial because it instills a habit of caution and respect toward firearms, significantly reducing the chances of unsafe handling.

The notion that a firearm should always be carried facing down is not one of the established primary rules. While it is generally advisable to point firearms in a safe direction, which may often mean pointing them down or in a specially designated safe direction, this specific guideline is not universally recognized as a primary rule of firearm safety. This makes it the correct choice in the context of identifying something that does not belong to the core set of rules for firearm safety.