There are exceptions to the rules for producing prototype weapons, that is why you have to be made 100% of your own design for them, you can't copy another mach

There are exceptions to the rules for producing prototype weapons, that is why you have to be made 100% of your own design for them, you can't copy another machine gun and claim it is a prototype. In order to register or sell a new machine gun design you need to have a working physical version already existing. You also need to make something that could reasonably be considered a prototype weapon you were making to legit sell to the government, some pipegun hardware store contraption obviously wasn't produced with the intention of being sold to the military or law enforcement and would not qualify as a prototype. Regardless, you should definitely speak to a lawyer before attempting anything like this, there are tons of local laws that you can break even if you are following state and federal law. And once you break a local law it becomes an illegal weapon and negates any legal standing you had with the state or federally.