does anyone have a good picture of how the 12th model SPR mounts on the gun. Is there a certain barrel thickness that the barrel will need to be machined to? Or is there different size tapered shoulders for different barrel sizes. AAC had a informative youtube video, does ops inc have something like it. I have narrowed it down to the AAC m4spr (price is main detterent) and the ops inc 12th model SPR.
thanks
thanks