Currently the most prolific locally made shotgun design being seized in Brazil. Someone out there, or some group of people is churning out hundreds of these things.
Extension spring zip-shotgun
Impro Guns
International Association of Ghost Gun Forensic Examiners
Impro Guns 
looks like it would pair well with mini-shells
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Open bolt blowback? Does it eject?
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Is this still for sale? ^^
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It looks like gas pressure would probably blow the shell out of the chamber when the bolt came back. I don’t see any sort of positive extractor though, so reliability may vary…
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