All my parts for builds have come from White Oak Armament or White Oak precision, I used to buy barrels chambered with bolts from them... not that I have my own lathe I could do it myself, however I’ve never seen anyone drill the gas port yet... so I have reading too do. I have built multiple HP competition AR’s so I have all the other piece parts, and as you showed headspacing the barrel extension isnt’ much different that you do with a bolt gun.

Thanks great information. In the posts.