From The Truth About Guns:

The bill was ostensibly intended to outlaw firearms without serial numbers. It banned homemade guns, 3D printed guns, even possession of the files for running a 3D printer or CNC machine for making firearms. It even outlawed slingshots, fer Chrissakes.

I talked to Mr. Nappen this afternoon and he tells me the law is quite clear that for a firearm to be legal in New Jersey, it has to have a serial number and the serial number must have been imprinted by a federally licensed firearm manufacturer.

That means your Daisy BB gun — which under the state’s expansive and idiotic gun control laws is actually considered a firearm — may have a serial number on it, but Daisy isn’t a federally licensed gun maker. As a result that Red Ryder in your kid’s closet now makes you a felon.