[gundog]

Looks like a Welrod has to have the bolt turned 90 degrees to open or close it. Is that happening in the video? And why use an exotic like that? I would think that something ordinary and disposable would be preferred.

[Governor Dinwiddie]

One important detail is that for the welrod to work for it's purpose, you must use subsonic ammunition, and base it on a bolt action firearm. See Welrod.