Quoted:
It seems the guy has been selling them on GunBroker & on SubGuns for a few months now ... if it was illegal for him to sell, wouldn't the ATF have busted him by now ?
ATF moves with glacier-like speed in these sort of investigations.
If they spot some bozo selling one example of an illegal item, they bust them asap. But if someone actually sets up a business, ATF's standard approach is to "investigate and gather evidence," sometimes for more than a year.... Then they raid the place, confiscate business records, and use those records to after the individual purchasers.
After all, which headline makes better PR for an agency always seeking more .gov funding:
ATF agents arrest man for selling machine gun kits
or:
ATF Sweep Nets 462 Illegal Machine Guns in 34 States
Two-year nationwide investigation shuts down internet sales ring
Bureaucrats know how to finesse these things....