Radical Firearms RF FP10.5-7.62x39HBAR-10FGS 7.62x39mm AR Pistol

A: Frank, since this is a "pistol" and the barrel length is less than 16 inches, it's illegal to put a stock on it unless you intend to register this as a "Short Barreled rifle" SBR and pay a $200 NFA Tax Stamp.

A: the second you put a stock on it, it becomes an NFA item

A: Harry, adding a vertical front grip to a pistol constitutes making an AOW and requires a tax stamp.

A: Harry, adding a "Forward Grip" on a pistol will change the classification to AOW "Any Other Weapon" and would have to be registered as an NFA Firearm and a $200 Tax Stamp paid to be legal to own. Example here : https://www.google.com/search?q=aow+ar+pistol&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj-ran09q_gAhWPl-AKHZ2_AccQ_AUIDigB&biw=1280&bih=618#imgrc=68XmMRGwhhabUM:

A: Adiding a 'vertical' handle to the fore grip of ANY AR pistol is in contravention of ATF regulations. An 'angled' fore grip handle is legal ... It's all in the angle of the added grip.