That supersonic device is legally, a FIREARM. Any device that launches a projectile with a "muzzle velocity" in excess of 500' per second, is by definition, a FIREARM. At 400 meters per second, and with my very ruff arithmetic, it is moving at around 1312 feet per second, which is ruffly almost twice as fast as the speed of sound, and well above the 500 feet per second limit before becoming a FIREARM. I don't know if that matters in the USA cuz most folks there are legally allowed to own firearms anyway but it makes a huge difference up here in Canada. I am sure that Turdope would have a huge problem with anyone making and/or owning any size of siege-weapon and considering that his Parliament Buildings are made of giant boulders, which was built in or about 1867, I would think that that arrogant little sock boy would have a huge problem with a siege weapon that specialized in knocking down buildings like that in a few hits. Nobody without some kind of really fancy licence would get that weapon clearance in anywhere but the remotest of locations. And never anywhere near where Turdope works.
One video and you've caught the eyes of a solid half-dozen of my favourite creators! I imagine your capacities are better spent offline but should you return to RU-vid there are thousands of nerds eagerly awaiting your next project!!
Ahh, good ol knex. I remember building powerful rubber band powered guns out of these in my early to mid teen years. My best design was an almost 5 foot long rifle that was powered by those massive and thick rubber bands you frequently see holding broccoli together. To withstand the extreme force of these bands, it was rather chunky and had four "pistons" rather than just one to reinforce it which pulled the launch rod along with it. It fired the medium sized yellow rods with fletchings added to them out of tape. To cock the thing I originally had a rotating crank ratchet system which I later upgraded to use two knex motors to crank it back for me. It could fire all the way across my yard which was pretty big, probably about 400-500 feet long. Your design is absolutely badass! Keep it up!