Ok so I'm completely dumbfounded here, I'm trying to get my new bow sighted in and I bought a tru glo carbon xs sight. Well the Allen screw to adjust the sight elevation and windage doesn't fit any of the metric or standard Allen wrench sets I have, they're all too big or too small and I just bought new sets thinking maybe I lost the one I needed, still no dice.... So what size Allen wrench do I need?