+1 on this. I screwed up and welded mine before I was planning on. It came out ok but I had to scratch some welds and adjust the tube. Use files for the fitting on the cocking tube and fit it tight. I’ve seen a couple of build where there is a big gap between the tube/tube but if you go easy on fitting you can get a nice tight meetup.
I’m a fan of the KAC rails and rails in general but I’m a bit old school with large man hands. I will like it more when my stamp rolls in and I can put the stock and VFG on it though. I have the top rail for it also but haven’t opened the box for that yet.