if it is registered as a pistol, it must fire like a pistol, that is fire it with one hand on the pistol grip. you can add a 40 in bbl if you want, it still doesnt change the config. as far as doing the glock thing, I would think that , as long as it can still be fired , as a pistol, since the wire stock, is readily moveable, or even with it deployed, it can still be fired as a pistol, then that would be ok, but i wouldn't hold my breath on it. however, there is no vertical forend pistol grip on it, nor can you put one on it, because now you have changed it to fire as a sbr, or too rifle like, assault like. and that is a big no-no.