and are worth something outside of the home. I favor the 60 gr Nosler Partitons, for controlled expansion and penetration. They are expensive, and only available from Black Hills as loaded ammo.
The 12 ga is not very viable outside the home. It's also not worth much inside the home. Try firing it without ear protection, at night, and see how well you can still see and hear, for instance. The 223 can be a handy gun, even with an effective sound suppressor mounted on it. The 12 ga cannot. The 9mm carbine is the choice for in-home use, over the shotgun, any day.
At typical defensive ranges (ie, 10 ft and less from the muzzle) the shotgun's pattern spread is at most 2" with buckshot, so you can easily miss a man with it. Birdshot, smaller than #2, will not reliably penetrate both a heavy coat and the sternum, beyond 5-6 ft from the muzzle. It's not NEARLY as good a choice as the ignorant "think" that it is for home defense.
I don't even bother to own a shotgun. I'll use either the pistol for home-defense, or the AR-15 for riots, storms, shtf type of real combat stuff. Those without lots of training should stick to the 9mm HiPoint carbine for "home defense", using CorBon 100 gr PowRBall ammo, not the shotgun. HITTING (fast enough to save yourself) is NOT a "given" in any attack, not with a shotgun, not with any sort of firearm.
The only thing that really helps your defensive shooting ability is lots of practice with your gun. Shotguns are not welcome at most indoor ranges, the 9mm carbine is. 9mm practice ammo costs a lot less than 12 ga shells, and the 9mm is a lot easier to handle than a 12 ga pump. This is especially true with one hand, as you use a light, open a door, use a phone, hold a kid, look under a bed or behind clothes in a closet, etc.
Power is only rarely an issue in civilian self defense. It's well proven that over 90+% of the time, if you get your gun out and "on" the attacker in time for him to notice it, he will not make you hit him with a bullet. Since it will probablyl cost you $20,000+ to defend your shooting in criminal court, and ANOTHER $20,000+ to defend it in civil court, not having to fire is best. You are responsible for every shot, and bullets and pellets do weird things (like richochet and hit innocent people).