take it off ***And destroy it****.
And we remember from the before times that a buffer tube that will accept a stock, and a stock you could put on it, even if that stock is on another rifle, is constructive possession of an SBR.
But honestly they don't need the conviction. They need to pick the right guy with a braced AR at the range, and preferably a 10/22 in one of these jurisdictions with a Sheriff that is not bending the knee, get a warrant based on seeing him with an AR pistol and stock (maybe on another gun), call the news and roll a tac team. The story will be "multiple weapons, including illegal SBR, and thousands of rounds of ammo seized by ATF/FBI joint task force. Sheriff refuses to enforce public safety laws. Federal law enforcement needs more agents to step in where the racist lazy Sheriff's won't." Film at 11.
I have to assume they will do something like that just for the chilling effect. The Revenuers can't let states and Sheriff's just ignore them (and federal law). That's how you end up the next Border Patrol with no funding and the president hating on your horse reins.