I have an ART II GI sniper scope. I tried it on one of my non-military rifles and found that I need more adjustment for elevation than allowed by the normal adjustment screw.

I noted that there is another ring concentric to and on the outside of the adjustment screw ring with equi-spaced markings and it has a single notch presumable for a special tool.

Anyone know the purposes of this outer ring? It is possibly a gross adjustment for elevation and the inner screw is for finer increments?