[supercat]

It is not a drum "clip". It is a magazine. Get your nomenclature right, or look like some MSM-like ignoramus.

Is it a magazine, or does it have a chamber for each round like a revolver? My understanding is that at least some shotguns use the latter design.

It's important to note, however, that NFA'34 defines as a destructive device any firearm with a bore >0.5" which the Secretary of the Treasury finds is not particularly suited to hunting or sporting purposes. Since revolving-cylinder shotguns as well as some box-fed semi-autos have been found to be 'non-sporting' they are taxed and restricted as 'destructive devices'. People who owned such shotguns at the time of the rule change were allowed to register them for free within a certain time of the rule change; anyone registering them after that (including anyone to whom they are sold) must pay $200.

[7MMmag]

I didn't look at the video, so was guessing it was like the otherwise here mentioned "street sweeper". Chatter in the heading comments further lead me to assume that it was magazine fed. I've never seen a revolving cylinder shotgun myself --- but now that you mention them, it sort of rings a bell. That, and guys will get around to combining different ideas, given enough time. I have seen a [ahem] handgun that had ten cylinders arranged in revolving fashion --- in get this --- 45-70 Government! Ka-boom! X 10, if you could hang on tight enough. Both hands, pretty much absolutely necessary, of course.

The infamous (to gun paranoids) street sweeper, had available for it drum magazines of (if memory properly serves) 10, 20, 30, and I think -- 50 rnds. The higher capacity ones were said to make the weapon a bit too heavy. 20 rnd magazines were said to balance and feel good.