It's a gray area. 26 USC § 5845 (e) vaguely defines the concept of an "any other weapon (AOW)" as follows:
any weapon or device capable of being concealed on the person from which a shot can be discharged through the energy of an explosive, a pistol or revolver having a barrel with a smooth bore designed or redesigned to fire a fixed shotgun shell, weapons with combination shotgun and rifle barrels 12 inches or more, less than 18 inches in length, from which only a single discharge can be made from either barrel without manual reloading, and shall include any such weapon which may be readily restored to fire. Such term shall not include a pistol or a revolver having a rifled bore *
While they can be concealed, handguns themselves are exempted by the last sentence. However, if the holster turns it into a gadget that's not readily identifiable as a handgun but fires bullets, it becomes an AOW. Think pen guns, cane guns, and that goofy H&K briefcase MP5.
From the ATF, in 1997:
During the 1970’s, ATF determined that various small handguns combined with certain “wallet holsters” fall into the “any other weapon” category and are subject to the provisions of the NFA. These wallet holsters are generally rectangular in shape, are designed to disguise the appearance of the handgun, and are designed to allow the weapon to be fired while it is contained within the wallet. The handgun combined with the wallet holster constitutes an NFA firearm.
That last part is how jerks at the gun shows get away with selling the holsters to unsuspecting buyers. As long as it's just the holster, it's OK. The problem arises when you stick a gun in it.
A conventional pistol or revolver which is possessed without the wallet holster would not be an NFA firearm. A wallet holster alone is not subject to NFA controls and cannot be registered or transferred as a firearm. Firearms contained in conventional holsters, trouser pockets, purses, gun cases, or various other forms of carrying cases have not been determined to fall within the definition of an “any other weapon,” even though it maybe possible to discharge a firearm while it is carried in such a manner.
Here's
another letter from the ATF which confirms the idea that if a device that conceals the nature of the weapon
and the weapon can be fired through it, it's an AOW. Both conditions have to be met.
So, the ones with exposed slides are
technically legal. There's still a risk of significant hassle until somebody figures that out, however.
Also, getting shot in the jiggly bits. Not good from what I've gathered.
(* Bonus points to anyone who knows where that last bit came from.)
) I'm not as worried about being able to shoot it from the holster, as I am giving a square print in my jeans pocket...