Mad John will just have to use an FFL. Won't stop or slow down legal gun owners, and it certainly won't slow down any criminals.
It will be a pain in the but for those that try to obey the laws.
A 2015 University of Chicago Crime Lab report suggested that inmates locked up for gun crimes avoid getting their firearms from sources that require any background checks
I wonder how much time & money was spent to reach that jaw dropping conclusion. Pathetic, and no doubt they spent time patting each other on the back.