great idea on using a end mill with one side removed ill gice that a try for a couple of projects. I dont have a small boring bar yet.
the triangle did ok but that bolt is hard and it catches on the groove. I rather put it in my rotery table in the mill and true the face to the pin hole. the pin ole on this bolt is about .004 out of true. a metrick end mill is just the right size. It dont take much. I hit the extractor some with a griinder and cut off wheel to move it back I also trimmed the back were it hits the bolt so the front didnt have to be trimmed as much. pretty easy and it seems to lock into place I caan always go more off.
the barrel is pressed and pinned into place and head spaced slightly tight on a go and just right on a hand formed round made form 7.62x51 nato brass with the neck ID turned. Im debating on a custom GB with optic rail or stock and doing somthing later.