I just noticed comparing my rear sight picture with the photos on the main page, my elevation ladder is backwards.  someone in the past must have removed it, and then forgot which way it went back on.  I will very carefully correct this. Fortunately, I have a Brownells screwdriver set.  Another thing I noticed is that the sight is graduated to only 1800 yards, but has the C stamp in the correct place.  Could this be a very early carbine sight, or an arsenal replacement?