The problem is the legal part; you can manufacture a full auto in your cave, doesn't mean you want to get caught owning, let alone selling one without permit You're already barred from owning a full auto without a permit, you're also barred from accessing some calibers, through regulations In the end, those are only administrative categories https://en.wikipedia.org/wiki/Automatic_firearm#Regulation Automatic weapons tend to be restricted to military and police organizations in most developed countries that permit the use of semi-automatic firearms. Where automatic weapons are permitted, restrictions and regulations on their possession and use may be much more severe than for other firearms.[1] In the United States, taxes and strict regulations affect the manufacture and sale of fully automatic firearms under the National Firearms Act of 1934 and the closing of the "machine gun" registry by the Firearm Owners Protection Act of 1986 (only previously registered automatic weapons may be purchased). A prospective user must go through an application process administered by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), which requires a federal tax payment of $200 and a thorough criminal background check. The tax payment buys a revenue stamp, which is the legal document allowing possession of an automatic firearm. The use of a gun trust to register with the ATF has become an increasingly popular method of acquisition and ownership of automatic firearms. ... Never say never >>You can always remove the processor and rework the gun to fire without And this could be construed as a criminal act in itself...