The problem with any kind of auto (semi or full auto) shotgun is how do you make it reliable, gameable, and still act like a shotgun? AEG would be a bitch to do because of the issue with feeding multiple BBs at once (though I still think it's possible). Shell ejecting would easily work but then you have to worry about shells, which reduces its usefulness. GBB is probably the best work, but also leads to problems with feeding and gas mileage.
If anyone ever actually does make ANY form of automatic shotgun, I'd love to see some of the classic semi-autos (such as the Benelli M1 or M2, or the M1014) as well as the Pancor Jackhammer and the AA-12.
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