What the bloody over-sized shotgun shell would fit that blunderbus?
OK, so it’s a simple muzzleloader, and probably as accuate as a carronade. Firing mechanism = ?? Slow matches with a broadside?
I was having similar thoughts as yours, but think it out:
The wood part appears to be a 2x4, which is 1.5 inches thick.
The pipe then would be 3/4. I just tried a shot gun shell in a 3/4” black iron pipe. It is a sloppy fit. The rim part of the shell will not fall into the pipe.
So the cap you see holds the shell into the pipe so it will not fall out the other end, so it’s not a muzzle loader. A small hole drilled into that cap would let a spring loaded casing nail or other small rod rod to act as a firing pin.
Note the object on top of the 2x4, in must be some sort of simple trigger to release the pin.
It would work. To load it, slide the retaining ring off the gun, remove the pipe. Cock it by pushing the pin back past the trigger catch. Unscrew the cap, put in a shell, screw the cap back on, place the pipe on the 2x4 stock, slide the retaining ring (strap) back on, and you are in business.
A 24” pipe would make it much more accurate. The 2x4 would have to be longer and add another retaining ring.
I personally would not have the guts to build one, let alone fire one.
12 gauge is close to 3/4”.