I can't see a .410 being very useful for self defense or tactical , unless you have a chicken or partridge trying to break into your house in the middle of the night.
I've loaded .410 shells for many years, and in many configurations, they simply have no power for much other than small very small game. I've played with slugs and a chronograph for countless hours and days that I'll never get back. The result is a slow speed 1/5 oz slug that has not much more energy than a .22 cal bullet. I've played with .000 buckshot in every imaginable load, but groups all over the place at 20 feet and has less energy than takes to get through a thick piece of plywood. Trying to keep four 000 ball in a row shot everywhere, or the group would barely make it through cardboard. Even the best grouping bird shot has no more than 3/4 oz lead, which in my opinion is not so good for offensive/defensive rounds when compared to what you can get out of a 12 or 20 gauge.
I can go on and on about experiments of trying to make useful loads for .410 other than small game loads, but most of them don't work very well at all. At the end of the day, a .410 make a wonderful gun for small game, but if you want it for anything else, you might want to revisit a caliber /gauge that that has some power before you fork out big cash for something that has more show than power.
The best shotguns are made in 12 and 20 gauge for a reason, and the prices reflect this.