Josh writes …

I recently completed a home-made 20x102mm (20mm “vulcan”) destructive device, registered on an ATF Form 1. This gun is a single-shot, breech-loading firearm that lobs out a ~1520 grain inert steel projectile at an estimated 3100 feet per second. It’s locking mechanism can be nest described as being a very crude “falling block action”. The gun sits atop an M2 tripod from my 1919A4 rifle, and can be “steered” with the traverse/elevation mechanism. The cartridges use electric ignition, which I used a Nintendo 64 controller to build the remote control inside. It delivers a brief, but very intense burst of 300V DC to the primer, through an insulated electrode in the breech block.

Very nifty!