Then there's the sighting corrector. We've worked out what most of the dials do (though we're puzzled as to why it turns around as the gun itself turns). However, we're not sure of the purpose of the white metal horizontal dial that is situated at the bottom. It has markings of 0 to 40 (which somewhat mirrors the vertical azimuth scale that's in front of the operator and goes from 0 to 400). Any ideas anyone ?