The ATF'nE's new rules regarding whether a given "brace" actually makes a given "pistol" into a NFA-governed "short-barreled rifle" are coming into effect.
Rather than take a lot of time condensing all TDF said last year about these braces, just click on the search link below. It's a short read to skim. But just to say here: People got silly and stupid, and it cost people, especially crippled people, a good thing.
Cats, Guns, and National Security: Search results for pistol braces (catsgunsandnationalsecurity.blogspot.com)
The video below is a reasonably honest run-through of the published point system for ATF'nE determination.