It’s actually a bit higher than I thought. The 175,000 “transferable” machine guns—the only ones that can really be owned by the general public—are what are left over from the finite supply of such weapons that were existing and registered (”lawfully possessed”) in May 1986. That’s why they are so expensive to buy.
The bottom line is, yes, it is legal for John Q. Public to buy and own a fully-automatic firearm, so long as he finds one of the few still around, jumps through the normal NFA hoops and pays the tax, and so long as he is willing to pay five figures for a gun with 30-year-old-plus parts and no warranty.
I won’t get into the whole issue with post-ban “samples,” which make up most of the remainder of the 490,000—you can find a lot written online about how an FFL can obtain one of those for personal use, but I think anyone who does so is taking a big risk.
Got into an argument today about full autos. My closing argument was to check online gun auctions for an M-16 in "good" condition. He won't find one for less than $20K............