In what became the most exciting college chemistry class ever, an Idaho State University professor demonstrated a really bad experiment. During his lecture he managed to shoot himself in the foot with a small caliber handgun he was carrying in his pocket. Specifics are sketchy, but we do know the gun was in his pocket and it never left his pocket, even after perforating pants pocket, shoe leather and foot.
Competition games require fast guns. They’re the thoroughbreds in the gun world — really fast, but finicky and at times fragile. Some can be highly modified to become uber-accurate with 1/30,000 tolerances, but if these guns fail to function, you might lose a trophy.
But when some miscreant is pointing a gun back at you, losing the “game” means death or injury. There’s no second place in a real gunfight and no alibis are acceptable for the gun you need to stay alive.
The concept is as old as the Colt Single Action Army and the Old West. In the frontier, ammo was often scarce and being able to shoot the same ammo in both your handgun and your rifle made perfect sense, so Winchester offered models in common handgun calibers. Interestingly enough, early rifles were not offered in .45 Colt since the rim of the pistol case was too small to reliably operate in a lever action.