I can't really think of a reason why the piston returns to the original position!!
any ideas??
I made a transparent QEV coaxial cannon out of the preform of a bottle.
This was inspired by a Nighthawkinlight's project, although I added a transparent barrel and had to make everything work with a wooden piston and o-ring seal.
The breech seal is just a piece of rubber from the inner tube of a bike tire.
Thanks for watching!