My friendly hippie Takoma Park neighbors might be surprised to learn that I have kept a Mossberg 590 with ghost ring night sights (tritium illuminated), extended mag and ventilated metal handguard as primary home defense weapon for fifteen years. It has had many hundreds of practice 00 buck and rifled slugs through it over those years, and never once has it faltered.
Besides the benefits mentioned by others more qualified, another advantage of a 12 gauge pump like the 590 is the variety of loads available for it, depending on what you are trying to accomplish in your close encounter. From beanbags to flashbangs to door entry rounds to rubber buckshot. Its all out there.
But the guy who taught me tactical shotgun (trains MPD) favored 00 buck and for very heavy or longer range work, rifled slugs. His logic is that, if you are reaching for the Mossberg, its a deadly force situation already, in which you may as well take advantage of the considerable firepower at up to 50 yards a 12 gauge pump offers.
A shotgun at indoor ranges is not a "death ray" that spreads out so much that skill and practice is optional. In fact, at the 7-12 yards at which most gunfights take place, the pattern of a load of buck is about the size of a very deadly fist. The point is that one must practice with the loads you plan to use. A lot. Accuracy with slugs at up to 50 yards with the ghost ring sights might surprise the uninitiated. I used to be able to get all of them in a dinner plate at that distance when trained up. Plus, they are devastatingly hard hitting. Think Civil War Mini Ball at higher velocity.
