Remember the YouTuber who built a 25mm revolver hand cannon powered by HHO gas? Well, he’s gone even bigger—all 40mm of it. Meet the 40mm Double Barrel Revolver Shotgun, a beast of a creation that looks as awesome as it is dangerous (and, yeah, we kind of love it).
The ammo for this thing is huge, and what goes into it? That depends. For slugs, he’s using ping pong balls. For the 12-gauge shells? Some massive pellets that, judging by the firepower in the video, you do not want coming your way.

As the name suggests, it has two barrels—and with an inline dual-trigger setup, you can fire each barrel individually or both at once if you’re feeling particularly bold. Like his smaller 25mm revolver, each round needs to be filled with propellant gas, and ignition comes from two sets of electrical arcs when the trigger is pulled. A cocking mechanism underneath rotates the cylinder to the next chamber, making it a functional, albeit very unconventional, firearm.
It’s an engineering marvel and a testament to how modern tech allows regular folks to design and manufacture their own weapons. While it may not be 100% lethal, a contraption like this could still double as a self-defense tool—no license required (depending on where you live).
That last part is crucial, though. In places like Singapore, where gun laws are seriously strict, owning something like this would land you in a world of trouble.
Images: YouTube (Flasutie).