This guy thinks he invented something new:
Little does he know the USA beat him to the punch with an actual product (for the AR-15 only). Remember this?
That was the Halix Chin Stock which quickly got swept under the rug due to embarrassment by a company now called Sintercore (which is still selling a 3D printed muzzle brake for $300 if that tickles your fancy).
Thoughts? Petition to bring back the chin stock? :P
Hat tip: Kris