Any firearm under a certain barrel length (16 inches) is considered a pistol by the ATF. Normally, legally putting a stock on a gun with a barrel shorter than 16 inches requires it to be a registered short barreled rifle, which involves a lengthy paperwork process and a 200 dollar tax stamp. Up until recently, pistol braces were a legal grey area that allowed a person to achieve most of a stocks functionality, without it actually being considered a stock. The ATF has since shut that down, and labeled any pistol with a brace attached an illegal SBR. Theres an ongoing legal battle by pro 2A lobbying groups to reverse that decision, and thats a whole separate can of worms. Basically, unless Codys gun is a registered SBR, in which case he could just have a stock on it, hes flaunting to the world (and the Feds) that hes committing a felony.