Sean, PM Bravo. He ended up purchasing 100 set screws at one point, I believe they already have the correct chamfer on them. I think it is a 5/23" allen wrench, same as the gas block. If you get one from the hardware store you will just have to grind down the point to get the slightly beveled chamfer you are looking for. I don't know length off the top of my head but I will search.