The Station Six and Welrod are manual action pistols. When he fires the first shot, you can see a slide go back and a puff of gas from the ejection port, so it's 100% not either of those. Based on the malfunctions and the moving slide, it was almost certainly some sort of Browning action pistol and more than likely a homemade suppressor, but possibly also a heavier rifle style suppressor without a Nielson device.
Internet has been a wild and amazing place today though, some really killer memes and jokes.
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