I’m afraid I have been somewhat remiss on photographing this build, but it’s quite a simple one in terms of components… The baseplate is an early war design which suits itself to precision rather than speed. The spiked arrangement on the bottom digs into soft ground to provide stability. The curved plate is your elevation control.
The bottom of the barrel/chamber, shown just after welding. The main body of the barrel is easily removable to remove the shell if you need to.
And the finished prototype! There will be a few modifications for production that allow the barrel to sit flatter for transport and the shell will have cutouts in the fins for lightness.
Something worth pointing out is that this is designed mainly for use with TAG shells to take out targets at long range or lay smoke screens, though you can put in any 40mm shells you like. During testing we did experiment with scatter shells and they were effective at clearing a wide area ahead of the mortar.
Also, dropping the shell is unlikely to set it off. The firing mechanism is sat well inside the shell and will only be fired if activated by something goes that far into it. This makes it safer than just carrying moscarts which can go off when dropped on their base.