Good day - Greetings Community.
I just built a close to M224 Mortar.
Double Barrel for safety reason ( 3inch on the inside - pressure barrel ) and the outside visual one is a 4 inch.
there is also a V cone Nozzle at the transition from combustion chamber to Barrel for gas velocity increase ( like a jet Nozzle ) to enhance performance again a bit.
The propellant is Hairspray which is introduced through the small 1 1/2 inch fitting with a sealed cap.
The ignition system is a commercially battery transmorer igniter for BBQ`s - the long electrodes are placed in the middle of the combustion chamber, ensuring a proper ignition of the propellant.
It works like a charm.
A Nerf Vortex Whistler when completely pushed down the barrel and with high elevation angle ( low range ) - still went almost 400 feet far and about 150 to 200 feet high. With a nice real sounding grenade whistle....
watch the movies...
the difficulty I faced is that with multiple shots behind each other - do I have a lot of Missfires... so ventilation from the burned gases is key.
I can overcome that by removing the filler cap before I charge something down the barrel - the airvolume from the barrel which is pushed into the combustion chamber - circulates enough to push out the burned rest gases and introduces again oxygen into the chamber.
I am also planning on different airsoft safe projecttiles all out of foam or even BB`s.
I shot about 2000 BB in the air - which are pushed out by a piston which is tethered to the Barrel ( in order not to to fly right behind the bb into the horizon ) - it looks awesome - a cloud of BB goes with that elevation I had about 150 feet far and falls nicely down like a rain - covering about 10 to 15 spquare feet....
perfect for airsoft.
I will build a few more and introduce real artillery strikes with the proper set of rules - for the acknowledging fair player of course.
a view photos and some test Vids...
https://www.youtube.com/watch?v=3xEPlFoAEKA
https://www.youtube.com/watch?v=xn-34gJk9Y0