Hi,
If you look closely at the rear sight, you will see that there are 3 thin lines on either side of the rear sight and one single thin line on either side of the screw adjustable part. The screw is used to set the height of the rear sight, the lines are used as guidelines.
On my 1917 LP08 the adjustable part is set to align with the center of the 3 lines.
Sorry for the bum scan quality, but I think it gets the message across anyway
