Okay, there are now gas operated AR's (be they DI or piston-powered). Several enterprising gents have built pistol caliber AK's. How about a .45acp or 7.62 TOK AK whose bolt locks up (edit: found a TOK conversion AMD Build in7.62x25 ) ? Such a beast could use standard receivers and carriers, with modified bolts and such (i.e. easier for those of us who are more-or-less technically challenged).
I'll take mine in pistol form, please.
In a related vein... would Rhino_66's M11 magwell be legal in a pistol version (I have one in my parts box)? It is not a vertical foregrip, nor does it utilize a detachable magazine installed outside the pistol grip (ATF-speak).