I first came across this patent whilst looking for something else in the vintage gallery, but I was intrigued and followed the trail back to a thread on here from 2019: https://www.airgunbbs.com/showthread...-experts/page2
I was looking for a new project at the time so decided to have a go at making one from the limited information available in the patent drawings:



It took a fair bit of head scratching to develop a design which could assembled and disassembled easily - I thought this would be important, as making it all work would take a fair bit of tinkering and adjustment. The power plant consists of a single cylinder and two matching pistons, each driven by half a Webley pistol spring. The spring guides are threaded to hold them into the cylinder. The cocking arm pivots are attached to a sleeve which slides on to the cylinder, the breach block bolts on to the sleeve at the front and through the cylinder into the trigger assembly at the back:



The trigger mechanism proved to be quite fiddly and still needs a bit of refinement. I added more adjustments than shown in the patent as I concluded that adjusting everything so it worked would be challenging - I was right!



Once I eventually got all the bits ready I discovered that it was very difficult to adjust the trigger to make both pistons release simultaneously so I made a temporary cutaway side plate so I could see what I was doing:



Once adjusted correctly the side plate was replaced and the gun fully assembled. The grip is carved from a scrap of Cherry to match the shape shown in the patent. The assembled gun:



And cocked:


The loading port is a bit larger than the patent showed - I though that having made a recoilless air pistol, it should be able to shoot pellets instead of BBs. The loading port to viewed from the top:



And cocked:



There isn't any form of anti beartrap so it is best to hold the cocking lever back whilst dropping a pellet in.
The shot cycle is not completely recoilless like the Diana model 6, at least partially because it could so with some more adjustment and refinement. It seems to be fairly powerful although I haven't measured the muzzle velocity it yet. I still need to make the sights so haven't done any accuracy testing and I will need to finish the metalwork at some point - this may all take a while yet though.