Play for keeps. Think ahaed. Kil lthe first five then see who wants to be next. Brenneke slugs are highly effective.
But I don’t carry a shotgun. I do carry a Glock mod 20, though.
If you can get it, the fully automatic Glock 18C with a standard 17 round clip in the stock... and two 33 round extended clips as backup should eliminate most flash mobs. Even large ones can be dealt with if you have 83 rounds (plus one in the chamber) to burn.
:-P
Plus, it’s more concealable than a shotgun.