• WW1 Periscopic Prism Co Ltd London Telescopic Sight Strip Down (by Valleysniper)

    The following article is published with the kind permission of Valleysniper. On behalf of MILSURPS.COM members, we'd like to publicly thank him for his support of this forum, as well the broader Lee Enfield collector community in general.

    Note: After you click on images to ENLARGE them, you may find they automatically size smaller in your browser's window making them hard to read. The auto sizing is your browser's way of keeping images entirely within the screen size you have set. If this happens, you will see a small box in the bottom right hand corner of the pic with four arrows point outwards. Click this box and the pic will EXPAND and open up to its normal size, so you should now be able to read any text and make out small details.

    WW1 Periscopic Prism Co Ltd London Telescopic Sight Strip Down

    By Valleysniper



    (Click PIC to Enlarge)


    I was asked by member Terrylee to do a strip down sequence of the WW1 PPCo scope, the most numerous of all the Great War sniper scopes used. There are about 4 or 5 variations of the PPCo scope that I have seen to date with minor differences, but the major visible differences being what I call the “Stepped” tapered ocular housing variant and the smooth tapered ocular housing variant. In this sequence I have used 2 scopes for reference.



    (Click PIC to Enlarge)


    1. Unscrew the brass ocular lens housing from the tube thread. If it is tight borrow the wife’s dishwashing rubber gloves for some purchase on the tube and housing. If it is really, really tight, then you might have to warm the threaded joint area up a little with a hot air gun or hair dryer. With the Stepped tapered variant, if you are unlucky, sometime the brass collar of the brass ocular housing will unscrew from the brass ocular housing and stay on the tube threads. If this happens you will have to remove collar clean up threads and Loctite it back to the brass ocular housing.


    (Click PIC to Enlarge)


    2. Pictured above are the 2 distinct ocular lens housing variants. For the Stepped tapered variant, unscrew the front ocular retaining ring/cell; again the rubber gloves may come in handy for purchase. The first lens is enclosed in a brass cell assembly and is retained with a brass retaining ring with a rolled over edge. Next remove the spacer (if fitted as not always). Then remove rear lens housing cell. The lenses can now be washed and cleaned using a ½” fine sable artists brush frequently rinsing brush and lens under tap to remove any contamination. Dry the lenses and clean with Isopropyl Alcohol, Methylated spirits or a good proprietary lens cleaner SPARINGLY as if you flood lens you may end up damaging the Canada Balsam that bonds the 2 elements of the lens together. We won’t go into polishing lenses in this article just assuming your lenses are good condition. If you need to remove a lens from it’s housing to replace as damaged, or if the Balsam has broken down, or is fungus infected, then the rolled over edge of the cell will have to be machined away in a lathe on a low speed to expose retaining ring and remove (see erector cell stripdown below as an example). Refitting is reverse of above, but don’t forgot to blow off any dust from lenses before fitting with a camera dust blower or similar.

    The smooth tapered brass ocular variant type PPCo scope, the lenses are easier to strip as the lenses are placed directly in brass housing, there are no cells. Note the orientation of the lenses in the picture, the 2 curved convex sides face each other in the housing separated by a brass spacer.




    (Click PIC to Enlarge)


    3. Unscrew the Objective Lens Brass “Beauty Ring” from front of tube and it's washer if fitted (not pictured). Remove the Capstan screws and square washers that adjust the prism that gives lateral adjustment in the scope. Mark their position beforehand.



    (Click PIC to Enlarge)


    4. Next we are going to remove the range drum and saddle assembly. First back off the range drum lock screw all the way out.



    (Click PIC to Enlarge)


    5. As pictured remove the central screw from range dial and lift the dial from the square key top of the lead screw. The engraved range disc can be further dismantled if you wish.



    (Click PIC to Enlarge)


    6. Next remove the 2 cheese head screws from the range saddle. Unscrew the lead screw anti-clockwise to remove saddle assembly, you might want to temporarily refit the range dial to help you do this if it is very tight. The lead screw can be removed for further cleaning if you remove the small screw from side of saddle housing.



    (Click PIC to Enlarge)


    7. Remove the 4 screws from the tube in front of range saddle position and at threaded portion of front of tube at 12 O’clock and 6 O’clock positions, Note the screws positions for re-assembly.



    (Click PIC to Enlarge)


    8. Next again with the help of your rubber glove, grip the end of exposed objective lens/prism/graticule housing and pull it out. If it binds you may have to rotate it as you pull or use some heat sparingly. Once you get it out handle it carefully to avoid damaging graticule assembly now exposed.



    (Click PIC to Enlarge)


    9. Pictured is the Prism assembly of the Periscopic prism scope in it’s dovetailed housing. Mark the prism housings position to prism assembly so it goes back in right way up on re-assembly.



    (Click PIC to Enlarge)


    10. This is the prism assembly removed, you can now clean the prism glass, remove old grease from male and female dovetails and re-grease with Molybdenum Disulphide (Grey grease).



    (Click PIC to Enlarge)


    11. This is a picture of the graticule pointer and crosswire, the diaphragm being held to the housing by 2 small screws. I will not cover pointer replacement or cross wire replacement here as if you are going to have a go, practice on something else first.



    (Click PIC to Enlarge)


    12. If you need to remove the objective lens cell for cleaning the back of the lens, grip end with the rubber gloves on again and unscrew it. Note again the lens is retained by a rolled over edge retaining ring and cannot be further stripped without resorting to machining. When you screw the lens cell back in after cleaning, grease lightly the threads and make sure the 2 retaining screw tapped holes line up again, as the screws go through exterior of tube, through objective lens housing and into objective lens cell.



    (Click PIC to Enlarge)


    13. Remove focus cover retaining ring and focus cover.



    (Click PIC to Enlarge)


    14. Next we will have to push out the erector cell assembly from inside tube. Using say a 14mm to 16mm socket and extension press it out towards objective lens end of scope tube carefully, ensuring there is something soft for it to land on if you push too hard. On NO account use anything that bears on the lens direct. If the erector cell sticks, try using some WD4O or similar sparingly inside tube but avoiding getting on lenses if you can. Also ensure the exit path of inside of tube is rust free and without burs to catch the cell on exit. Do not resort to hitting your socket/extension with a hammer, try a little heat on tube to expand the tube a little. The reason we are removing erector cell in this direction and your choice of socket size is that those scopes that are missing their original single piece ring assembly usually still have the mounting ring retaining screws still protruding through tubes. Even if your scope has no sign of the screws on the outside of tube the remains of screw thread sometimes still remain protruding in to tube on inside.



    (Click PIC to Enlarge)


    15. As you are pressing erector cell out first the range saddle reinforcing ring will come out, or if you are lucky will come out without any help in first place, or if you can get your finger in tube pull it out first.



    (Click PIC to Enlarge)


    Here’s a picture of erector cell, note it’s orientation; the smaller lens faces the objective lens.



    (Click PIC to Enlarge)


    16. Finally, to strip the erector cell to clean inside of lenses remove small screw and unscrew the smaller lens housing. You cannot unscrew the larger lens housing, to clean lens, you need to wash and reach in with cotton buds. To remove the lenses to repair damage, also pictured at bottom is another erector cell, this had a damaged small lens when purchased and the larger lens that had to be re-cemented as the Balsam had failed. Note the rolled over edges have been machined off exposing internal brass retaining ring. How you retain them back is a matter of choice solder, epoxy etc or if you have access to a lathe with threading capability thread the housing and retaining ring.

    Assembly is the reversal of the above, but lightly grease the inside of tube after cleaning it and moving parts, threads and underneath saddle to help waterproof scope.

    I hope I have covered most things and you now feel confident to have a go. If you don’t feel confidant don’t have a go, there are a few forum members on this site capable of stripping scopes, replacing graticule wire, pointers and re-balsaming lenses.

    Finally if anybody can help, I am looking for a spare PPCo erector cell lens as pictured above damaged, please have a look in the spare parts box.

    Collector's Comments and Feedback:

    1. The Lee Enfield by Ian Skennerton (2007) - ISBN: 9780949749826 is an excellent general reference book on the evolution of Lee-Enfield rifles, however, it doesn't go into great detail on their use as sniper rifles. Ian Skennerton published an earlier 266 page work in 1983 called The British Sniper (British & Commonwealth Sniping & Equipments 1915-1983) - ISBN 0 949749 03 6. For anyone wanting a lot more detail research with pictures covering the evolution of sniping, this is an excellent supplement to his later work. It is out of print, so I'd suggest you use a "Google" search on the title to see if you can find a copy from one of the rare used book sources on the Internet. I found my copy on eBay. ....... (Feedback by "Badger")

    (Click PIC to Enlarge)


    Note: The opinions expressed herein or statements made in this article are solely those of the author, and do not necessarily reflect the views of the Military Surplus Collectors Forums, or the ownership and moderation group of this site. MILSURPS.COM accepts no legal liability or responsibility for any claims made or opinions expressed herein. Also, please note that neither the author nor MILSURPS.COM recommends that any member of these forums, or a reader of this article, try this type of experimentation without the proper knowledge, equipment and training.
    This article was originally published in forum thread: WW1 Periscopic Prism Co Ltd London Telescopic Sight Strip Down (by Valleysniper) started by Badger View original post
Milsurps Talk Radio