I am just glad you like it! You really don't need an extension to use the Briley handgaurd with the gun, I ran it with the stock endcap for a bit (pic below). Sidenote: Never thought about taking off the spring retention cap for more rounds, that is a really cool protip that I wish I knew before I got the extension.
I got you on the pics, attached below. I hope the angles are good, please let me know if I can show any specific sections a bit more clearly.
If you look closely at the M-Lok slots around the KAG you can see the rubber inserts I am using. I have those there to prevent gas from getting to my hand, but I have not ran the rail without them so I don't know how much of an issue it would really be. They were cheap so I see it as a non issue either way.
Got any other questions feel free to ask, I will help where I can!