I have a legit 16in Kac upper. It's the Mod 2 with the 3.1 bolt and the Ambi charging handle and the 3 prong flash hider. Nothing wrong with it. I just grew bored of it to be honest. I've shot a couple hundred rounds through it at most. If you have any questions or anything just reach out.
I am open to offers! Let me know. Even if it's a 16in upper with cash on top