My Grandfather's old Ward's Western Field bolt action .410, with 3" #7 shot leaves a hole slightly bigger than a beer can in 1/2" plywood. With a "smattering of pellets" around the primary impact at 15 yds.
Sure it's a football field long, and was designed for rabbit, squirrel, dove, but remove the threaded choke from the end of the barrel,
put a slug in it, and at 25 yds, will hit a target harder than a 45Colt. More than adequate for SD.
That's from a quirky, cheap .410 over 60 years old. Put it in a small easily mobile platform, and at SD distances will damn sure work. Is it my first choice? No, not really, but I don't think anyone is going to be threatening me anymore, if that's all I have time to grab and fire. If I cut 7 feet off the barrel, it would be a bad a** bolt action,,...but I'd get a Judge instead....
just my .02 cents.