However, there is a note of caution with this happy tale. It is still possible to construct a short barreled rifle from a brace equipped pistol. The letter explains “…an item that functions as a stock if attached to a handgun in a manner that serves the objective purpose of allowing a firearm to be fired from the shoulder may result in ‘making’ a short-barreled rifle, even if the attachment is not permanent.”
As you may remember, I’ve contended that if you purchased a brace with the intent to build a gun that would be fired from the shoulder, if the barrel length is less than 16 inches or the overall length is less than 26 inches, you’ve just created a short barreled rifle. Why is that?
The NFA defines the term firearm to mean among other things “…(3) a rifle having a barrel or barrels of less than 16 inches in length; (4) a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length;…”
The term rifle is defined as “a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed cartridge to fire only a single projectile through a rifled bore for each single pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed cartridge.”
Key point being that it is intended to be fired from the shoulder. As such, you would have a firearm (Short Barrel Rifle) under the NFA which would be subject to its controls.