I think you might be underestimating what a "zip gun" can be. Yeah, a "bang stick" is a couple of pieces of metal pipe with a nail for a firing pin. It works o

I think you might be underestimating what a "zip gun" can be. Yeah, a "bang stick" is a couple of pieces of metal pipe with a nail for a firing pin. It works once with a 12ga shotgun shell - but a Sten SMG can be made from the same sort of materials, and is an effective SMG. They cost about $10 each to make in 1942. Plans are dead simple to find: https://duckduckgo.com/?q=sten+plans&ia=images&iax=images https://duckduckgo.com/?q=sten+plans&ia=images&iax=images Here's a thread on another forum where a guy builds an AK receiver (which is much more difficult to get right) from a shovel: https://www.northeastshooters.com/xen/threads/diy-shovel-ak-photo-tsunami-warning.179192/ https://www.northeastshooters.com/xen/threads/diy-shovel-ak-... Check out this 9mm machine pistol, produced by R9 Arms: https://www.thefirearmblog.com/blog/2015/08/11/mystery-9mm-machine-pistol-seized-europe/ https://www.thefirearmblog.com/blog/2015/08/11/mystery-9mm-m... There's one problem with that - there is no such company as "R9 Arms". These things have been showing up all over Europe for the past few years, and they're definitely a "professional" product... made by a company that doesn't exist. The best guess is that they're being made somewhere in Croatia, but to my knowledge that's based only on the fact that several were seized there shortly after they appeared. The fact is, it's easy to make a firearm. It's actually easier to make a full-auto firearm than it is to make a semi-auto - a semi-auto is effectively a full-auto with an extra design step to include a disconnector that prevents it from continuing to fire.