The US has used shotguns in combat since its earliest days. I personally know that in ‘Nam the point man with the 12 gauge and buckshot was feared and effective. The is no better short range killer.
That’s why I prefer the 410 Taurus Judge with bird shot as the first one or two rounds to fire. At 50 feet it’s a quick draw point and shoot weapon that covers the entire area of a 2 ft wide by 3 ft high target. The other holes have either steel balls or 45 cal for more carefully aimed shots. I cannot think of a better self defense weapon when the target shoots back.
I believe the US Marines had an officially sanctioned shotgun for use in the Pacific during WWII.