That muzzle device, tho
Labeled the “Combination policeman’s truncheon and extension pistol-barrel,” by its WWI-era inventor, Edward Norton Moor of Oakland, California, the device shown above is a hollowed-out impact weapon capable of coupling to the end of a revolver while still allowing the handgun to fire.
Not intended as a suppressor — an iffy prospect for most revolvers other than the gas-sealed Nagant M1895 and similar — Moor’s 1916 patent application for the device says plainly that, “The object of the invention is to provide an improved form of a policeman’s truncheon which will serve as a barrel extension of a pistol.”
I can’t find a reliable source for just how many of Moor’s devices were made, but, at least a few examples were produced by the Automatic Screw Company in California, with a 1919 patent date.


To what purpose?
The patent just calls it a barrel extension. It would likely add some fps to the velocity but other than that it seems like a wonky idea. That’s likely a big reason why nobody bought them
B.O.B. Getaway kits, turning a Pistol into a kitbash Carbine…
I guess it’s a thing. I remember when van Cleef pulled out that three foot revolver. It was a big hit.
Not exactly! van Cleef had two Colt SA Army “Bluntline Special” .45 LC Revolvers in the movie. An Bluntline with 18-inch barrel in his Saddle Bag and a Bluntline with 10-inch barrel fitted with a Stock that he carried with him…
Are these Barrel Extensions still being produced? I can see there potential usefulness in a BOB kit where Minimum needs can be Maximized