ATF Ruling 2010-4 - Certain AR/M-16-style Air Guns Classified as Firearms
This is an ATF ruling that was briefly posted, then taken down--but not before Google made the copy I've linked here. Apparently the ruling has been rescinded.
At first glance, the story seems pretty silly, even considering that they changed their mind-High-end Airsoft replicas counted as guns, because they could theoretically be converted. Although the replicas in question aren't the chintzy plastic things you see in Walmart, they are still essentially toys--More plastic, and the metal parts are mostly a zinc alloy similar to what is used in Hot Wheels or Matchbox toy cars.
It gets more complicated than that.The ATF distinguishes between 'gun parts' and 'The Gun'. Parts are mostly unregulated, but a bare frame or receiver with none of the parts needed to make it fire is considered The Gun, subject to the same regulations as a fully-functioning firearm. Like a number of rifles, the AR-15/M16 has a 2 piece receiver, with an upper and lower. In most 2 piece designs, the ATF says that the upper is The Gun. The AR was in use before serial numbers were required on The Gun, and Colt was putting the serial number on the lower. Apparently rather than make Colt move the serial number, the ATF simply declared the lower as The Gun on AR-type rifles, despite the inconsistency with other types. Had the ATF been consistent rather than expedient, convertibility of Airsofts would not be an issue--while there are similarities between the toy and real lowers, the uppers would be nothing alike.
The toy lowers did not work with a real upper out of the box, the ATF had to modify them. This is another issue. With enough work, it is possible to make an AK-47 receiver (The Gun) from stamped sheet metal, a zip gun from an old-style car antenna, or even a handgun from a billet of steel. These things obviously start out as 'not guns', and at some point turn into guns. The standard is typically 80% complete before they are officially a gun--although I don't know how you measure 80%.
So, did the ATF have to do more than 20% of the work to make these toy guns fire real ammo?
Another interesting question--what if the toy lower won't fit any current upper without modification, but someone builds an upper that does work? Would the lower still be considered The Gun, or in this case would the ATF consider that upper to fall under the 'non-AR' rules, and consider it The Gun?
Or should this be considered in the same way as cap and Ball pistols? They are loaded similarly to muzzle loaders and are not considered firearms. The cylinder to convert to modern ammo is merely a gun part, and is also not regulated--but once assembled, it is now legally a gun.