AAC 300 Blackout Upper 9"

[bassani]

http://www.advanced-armament.com/300-BLK-Upper-9-Barrel_p_461.html

I'm not familiar with upper forestocks that look like that. what are you supposed to do with the side holes that are there instead of a quad rail picatinny rail

 

[rbdub474]

Re: AAC 300 Blackout Upper 9"

It is the KAC URX III. It is made so you can customize the setup to your needs. You can get a kit like this with the parts.