In reference to the special aperture rear sight with fine adjustment screw on the top, they were all Winchester made and converted by the British. All had the original Winchester rifle serial number on the back (as per unconverted Winchester sights). If Serial No. is barred out, it means that sights were taken off rifles, converted at Enfield, and then the sights were sent to WW1 sniping schools to retro fit on existing rifles at the school. If Serial No. is not barred out, then the same conversion process occurred, but the sight was put back on the original rifle held at Enfield. From the 30 or so that I have seen the ratio of barred out to not barred is 70:30 The giveaway on the fakes is a slightly larger adjustment knob with cross checkering. Real ones like the one mounted on the rifle which is the subject of this Knowledge Library entry (see pics below), have vertical lines on the knob...
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