When I acquired my Webley Mk 3 Supertarget a few years back, I was immediately intrigued by the well-designed and beautifully made Parker-Hale rear sight. Over the years I have managed to accumulate some other goodies that complement this lovely bit of kit.
This first photo (below) shows the OEM rear sight, the Parker-Hale model PH 17. The basic model was made with different mounts adapted for many airguns and rimfires, this is a "PH 17B" designed specifically for the Webley. It mounts via two screws drilled and tapped directly to the receiver tube. The large PH 60 eyepiece has six different aperture opening sizes. Unlike other iris units that use a complex overlapping leaf assembly like a camera lens, this is a simple disk, offset from the center of the eyepiece and rotated to bring the different size holes into the center. The PH 60 is often seen with a small eyeshade of the same diameter as the eyepiece body--note the threads visible at the rear of it--but this bit was apparently not supplied by Webley.
If you look closely at the elevation adjustment scale, you will notice that the marks on the standing and movable portions are spaced differently. This didnt make much sense to me, until I realized that a different pair of marks aligns, with every fourth click of the adjustment knob. Once the gun is zeroed, the sliding portion of the scale is adjusted to align the two zero markings. Then any subsequent changes needed can quickly be interpreted--with a little practice you can quickly tell exactly how many clicks you have moved the sight. It's a skill similar to reading ten-thousandths on a micrometer. The windage scale on top of the sight works the same way.
The shot below shows a different eyepiece. This came from a massive PH 25 sight, similar in quality to the famous Redfield International and often seen on the BSA Martini rimfire match rifles. The eyepiece itself is similar in appearance to the PH 60, but is somewhat more robust and with a slightly different range of aperture sizes. The eyeshade is not rubber, but a chunk of steel that threads into the eyepiece. The front of it is blued, but the rear as you can see has a matt phosphate finish to reduce glare. Its a beautiful gadget and really adds a touch of class to the air rifles overall appearance.
Finally is another rear sight, the Parker-Hale model PH 16, which was fitted as a factory option to sporter versions of the Mk 3. Again, many versions of it were made for other guns, with this "PH 16M" specifically for the Mark 3. While it sits much too low to work with the Supertargets globe-type front sight (sporters had a short simple post foresight), it obviously mounts into the same holes.
This unit is a compact and completely ingenious design. Note how the entire windage mechanism is contained in the slender center arm, with an annular adjuster knob and the tiny eyepiece at the end. It has a wonderful floating ghost ring sight picture that--unlike a bulky target sight--leaves the area around the target almost totally visible. Note also how both the elevation and windage scales can be read at a glance from the rear of the sight. This sturdy, simple, and elegant design may be the nicest sporting iron sight Ive ever seen.
One last detail...the windage arm folds completely out of the way if needed. In the old days shooters sometimes used a folding leaf sight sighted in for short-range shots, with the peep sight zeroed for more precise work at a distance. One could thus be ready for two different situations in a flash!