Bryson - (1) One cannot attach any device to the rear of the firearm that was DESIGNED TO SHOULDER THE FIREARM .. without the ATF $200 tax stamp. To do so is to create a 'sort barreled rifle' a felony. One can attach any of the various pistol 'braces' being sold these days. as one might desire - they re not designed to be used to fire the firearm from the shoulder. (2) One can not attach a VERTICAL forward 'pistol grip' to the front portion of the rifle. To do so, again, could land you in jail. (One CAN add an 'angled' forward grip assist handle. Just not one that sits 90 degrees to the barrel.

Bryson, Ar Pistols can have a "Brace" instead of a Shoulder Stock to still be classified as a Pistol. You cannot add a vertical grip(adding a vertical fore-grip to a pistol makes it an AOW subject to the requirements of the National Firearms Act (NFA), stock or Suppressor without registering as an NFA Firearm "SBR" Short Barreled Rifle and paying the $200 Tax Stamp.