The bolt stop screw is a real thing, as noted by the headcount earlier. It is, as far as I am aware, the only wart on the rifle. I currently have three. I've looked at the stop screws under magnification, and they are significantly variable. The part was designed poorly, and then some are machined much worse than others with circumferential grooves right at the "snap here" stress riser corner.
Fortunately, you can deal with it by having your smith machine a small shoulder bushing and putting a properly manufactured M3 screw through it. He'll have to do a tiny bit of inletting on the stock to clear the bolt head, but it will be rock solid.
Would also be possible to drill and tap it to M4 and just sleeve the screw, making it even beefier.
