Jeff Cooper's four rules of firearms safety are simple. They're also pretty ingenious in that to really ruin someone's day, you generally have to violate more than one of them. If you peruse the news for negligent discharges (more often than not incorrectly called "accidental discharges"), they're commonly cleaning "accidents" and holstering "accidents." And quite a few are the result of trying to catch a dropped gun.
Whether it's guns falling from the pants of star athletes, hunters trying to catch a falling rifle, servicemen grasping the trigger of a falling gun during cleaning or someone shooting himself in a rather sensitive area because he tried to stop the descent of an unholstered pistol, these incidents, while rare, do happen.
An obvious lesson that can be learned from some of these cases is to always carry a handgun securely in a proper holster. Yet, an equally intuitive lesson can be learned from this type of incident: Do not try to catch a dropped gun.
With extremely rare exceptions, modern firearms will not discharge if they hit the ground. Hammer blocks, firing-pin blocks, transfer bars and safety notches are found, often in combination with each other, in the vast majority of modern guns. In fact, some states, like California, require drop safeties on all guns sold in the state.
When you drop a gun, you've inadvertently violated Rule 2 since you cannot control the direction the muzzle is facing while gravity has its way. What you can control is not introducing even more danger to the situation.
You can make the problem much worse by trying to catch the falling firearm. Your finger may land inside the trigger guard, and you've now violated Rule 3 of firearms safety. That combination can be disastrous. Let the gun hit the ground. It may get a scratch on its finish, but you'll live.
While catching a dropped gun is clearly a violation of two of the four rules of firearms safety, it may warrant its own place in the rules to emphasize its importance. As they say, "If it saves just one life…"