Why is it illegal to own a machine gun?
It’s not, under certain circumstances. One of those circumstances being not living in the PRK (California).
It was the Wickard v. Fillburn decision in 1941 that extended "interstate commerce" to essentially "all" commerce.
The Feds had to pull some dirty shenanigans to get a muddy decision from the Supreme Court in the Miller case, in 1939. That case was used by later Progressive appellate courts to rule exactly opposite of what the case said, making machine guns illegal to own without paying the $200 tax (about $3500 in today's dollars).
Then, in 1986, the Democrats did some dirty tricks to put in a ban on any further manufacture or importation of machine guns for citizens not in the government.
Since the National Firearms Act of 1934, the Gun Control Act of 1968, and the Hughes Amendment to the otherwise-good Firearm Owners Protection Act of 1986....
Its not. Its illegal to not have a tax stamp for it and its double illegal for a felon to be in possession of one.
L