I'm with Tom on this one.
Semi auto shotguns are reliable.
Yeah, I get a little twitchy when people say that pumps are preferable to semis because of reliability, at least when speaking of shotguns. I've been into competitive clays in the past, and followed the careers of some of the world's top shotgunners. Not avidly, you understand, but in passing. People who break thousands upon thousands of clays without a miss. People who throw 10 clays in the air 1-handed, and hit them all. People whose reputation and livelihood depend on a combination of reliable equipment and finely-honed skills.
And you know what? They don't shoot pumps.
Sure, some of the trick shooters, like Tom Knapp, will use pumps for part of their show. But for the jaw-droppingly impressive feats, the semi is always in their hands.
I don't say this to disparage pumps. I like pumps, and were I to use a shotgun for HD, it would either be a coach gun or a pump. But I would make that choice because I can keep a coach gun condition 2, or a pump condition 3, indefinitely. And I can unload either without having to run ammo through the chamber. For a semi (at least, for a spring-recoil semi), that last part isn't really practical.
Of course, the Saiga changes everything. That would also be a strong, strong contender for me, were I to contemplate the home shotgun approach.