I decided to post it now as there seems to be a considerable interest in spring-piston type airguns on the forum at the moment and some might find it a useful reference. It was quite a powerful creation for my first project, it would put a 6mm BB clean through a CD case.
The prototype is a bit dusty from hanging on my wall for so many years and is a bit worse for wear but you can see from the diagrams what it originally looked like. The drawings are self explanatory but of course any queries are welcome
