cause there have been questions on other forums, I have taken some pics to try to set some things more clear.
My rails and QRC are Pre-production ones. Compare the red numbers with the NN User Guide.
BTW: I placed a 350 gr 10 cm circle cut paper with cut out 7mm center for screw and the two anti twist screws - 6mm - to use it as reference to check LRS = Lower rail Setting
I turned the QRC 55 lower rail clamp around with the knob showing to me to get a free view for LRS Test.