Priscopic Prism Company Scope and Mounts.

Hi all,

Have recently acquired this P.P.Co scope (it's my first of Great War vintage).

https://www.milsurps.com/images/impo...DSC03243-1.jpg

https://www.milsurps.com/images/impo...DSC03244-1.jpg

https://www.milsurps.com/images/impo...DSC03245-1.jpg

https://www.milsurps.com/images/impo...DSC03247-1.jpg

https://www.milsurps.com/images/impo...DSC03248-1.jpg

https://www.milsurps.com/images/impo...DSC03249-1.jpg

https://www.milsurps.com/images/impo...DSC03252-1.jpg

https://www.milsurps.com/images/impo...DSC03254-1.jpg

https://www.milsurps.com/images/impo...DSC03255-1.jpg

https://www.milsurps.com/images/impo...DSC03256-1.jpg

As you can see, it's in excellent condition, still retains it's finish (apart from the polished brass components), is mechanically sound internally (with no fogging or delamination of the lenses) and still has its original P.P.Co SMLE mount.

First of all, I'm looking for a bit of history. I gather these were made between 1916 and 1918, also that its one of 4830 mounted to SMLE's. Is the 1837 number on the mount the scope serial number, with the numbers stamped onto the dovetail the original rifle serial number?

Secondly. One day (hopefully soon) I'd like to have this re-mounted onto an SMLE. Does anyone know where any engineering drawings of the mount base may exist so I could have one manufactured (or better yet does anyone do reproductions?)






Thanks :)

Paul.

I do reproductions & I'm currently waiting for the next batch to come in. I am also located in Sutton Coldfield just a stone's throw from you. Suggest you pm me if interested to take it further.
The serial engraved on the top of the mount is the rifle serial. The two large holes at each end of the flat are I am afraid post-War additions, but not a major pronblem. You are lacking the spacer & tensioning spring that fits along the one edge of the dovetail (where the two small screw holes are), but again, these can easily be made from a piece of spring steel.

You have a nice find Paul.

ATB.

Nice find, but a horrible scope. One memoir I read opined that they should never have been accepted for service. I think that might have been Hesketh Prichard too.

No matter, they're part of the history and a great place to start. When you get an Aldis No2 or No3 you will be amazed by the difference. Aldis produced some really superb glass. Years ago I traded for one with a German collector who has hundreds of scopes, and even he was impressed!

Thanks for the replies so far :)

I take it the scopes were not individually serial numbered since I can't find another number on the tube? What would the numbers on each end of the dovetail denote?

Yes, the holes on the flat are a post war addition. When it came it had another mount with dovetail fitting slid on and screwed in place, I just removed it but the holes are rough so will need some work to flat the rough spots.

Roger, thanks for the offer, when do you plan on having the mounts finished? What does the tensioning spring look like (I did wonder what those small screw holes were for)? As none of the pictures or diagrams I have seem to show it.

I must admit I was chuffed to bits when I bought it, as I never really thought I'd own one due to the rarity of them.






Paul.

Hi Sniper 1944. Drop me a PM & we can 'talk' by email. The specimen mounts are with the machinist now, but they are notoriously slow. However, they get done eventually & are worth waiting for.
ATB.

Hi Paul,

I’ve got the same model of scope, serial number B4486. It’s interesting that the serial number on mine is also stamped on the dovetail part of the mount (where your one seems to be a different number to that stamped on the top -C1772)

The 2 digit number on the mount on mine is 14, so I guess maybe an inspectors mark?

I have some good pictures of it, so if you interested drop me a PM with your email address….

https://www.milsurps.com/images/impo...DSC_3656-1.jpg

Email sent, but heres a quick picture

Thanks for the replies everyone. I'm now knee deep in research while trying to track down a suitable SMLE :)

I've just purchased "Sniping in France" as well, are there any other definitive works on WWI sniping that I should be on the lookout for?






Paul.

Sniping In The Great War by Martin Pegler is a good book.

I am currently looking for a complete mount set for my scope. I have the complete scope with it's carrying case but no parts for the mount. I am also looking for someone who can tell me how to remove the rear ocular lens from it's mount. I need to remove the lens assembly so I can split the lens and re-balsam them. Any help would be appreciated.

Unscrew the counter cell (the lens retaining ring) from the tube, tip the rear lens out, separate and re-cement is the way that I have always done it. But don't just do one lens, always do both

RWDAVIDSON

There are 2 versions of the PPCo ocular assembly, see my strip down article and picture of the 2 different ocular assemblies I did here:

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

Sounds you have what I call the stepped tapered ocular assembly where the front lens is retained in a cell with eye ring held in at the rear with a ‘rolled over’ retaining ring. The rear lens is retained exactly same way in its cell. The 2 rolled over edges of cell are the convex side of lens and face each other when fitted. Sometimes there is also a separate spacer ring between cells but not in all.

First of all accurately measure the width of the cell you are to repair and record it. You will then need to carefully turn down outer edge rotating slowly in a lathe until you get down to the inner ring near to the edge until it falls off, BUT watch the lens does not fly out of housing and get damaged. You could do final turning down by turning lathe chuck by hand or using a hand crank, you could also hand file. After turning down you should be left with a step, if you are lucky the retaining ring will come out easily but not always, it is also likely the lens might have balsam from between lens elements that has squished out of elements and cemented lens to inside of cell. Warm the cell and lens with hairdryer on hottest setting and wearing gloves (not rubber) gently start pushing lens out towards rolled over ring side, effectively removing lens and retaining ring same time. Take your time and keep the cell and lens hot regularly checking you are pushing lens out squarely and equally, if you get up too much of an angle on lens try and get square again as you can easily chip edges of lens and Peter has just sold last set had made.

If all comes out successfully and lens has not fully separated I always mark edges of lens elements so when they are re-balsamed they are as left factory hopefully the 2 elements being optically centred by factory (although some PPCo scopes have some serious optical problems that are factory original).

To retain your freshly cleaned and bonded lens in its cell the retaining ring can now either:

A) Be carefully bonded in with clear epoxy obviously ensuring none gets on lens outer surfaces.
B) The stepped edge/retaining ring soft soldered and neatly finished.
C) Thread inside of cell and make a threaded replacement retaining ring, this is the best method but time consuming and costly unless can do yourself.

You will then have to make a spacer (or wider replacement spacer) to recover any lost width of the lens cell after your repair otherwise the rear lens cell will rattle in the ocular bell between it and front lens cell.

Hope all this makes sense?

I have very carefully reviewed the dis-assembly and assembly article, it is a wealth of information. I have attached a photo of the scope for identification, and some closeups of the lens assembly. The rear most lens looks like it is missing some type of threaded ring? I can see what looks like a faint roll over line on the opposite side with a slight amount of solder showing. Is this the side I should remove in order to get the lens out? The innermost lens is perfectly clear, and I am somewhat hesitant to take it apart since it appers to be in very good condition.Attachment 37771Attachment 37772Attachment 37770Attachment 37775Attachment 37773Attachment 37774

The threaded inner of outer lens cell with built in eyering (nearest eye) was for the engineering machinist to hold the part on a threaded holder whilst turning boring and threading. Its the opposite side of this cell you want to machine off the rolled over lip down to depth of inner retaining ring. Don't be tempted just to machine off very edge, come back in about 1 mm to 1.5 mm from very edge to stand a chance of removing all of beading over of outer cell edge to inner ring.

I cannot see from pictures posted any signs of solder on cell that needs repairing and I just removed one from one of my scopes to compare. If there is suggests repair done already, but looking at the degradation of the Canada Balsam bonding the 2 lens elements it's looks like its been there for almost 100 Years now.

Let us know how you get on.

Quote:

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Originally Posted by Sniper1944

T
I've just purchased "Sniping in France" as well, are there any other definitive works on WWI sniping that I should be on the lookout for?

Paul.

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For those that want a great read, check the MKL for this book.... ;)

Milsurps Knowledge Library - Sniping in France 1914-18 (by Major H. Hesketh-Prichard DSO, MC.)

Regards,
Doug

I will probably not be able to work on the lens this coming weekend - opening day of deer season here. I will be working on the lens weekend after this. I will take lots of photos as I dis-assemble the lens carrier and post them here.

I wonder if there is a lesser way of improving the crystallized and cracked balsam - if that is the main optical problem? One of the regular forummers was about to take apart a telescopic sight, found things a bit stuck, and used a solvent to try to loosen the balsam. Not sure which solvent. He forgot about it for a while, but when he came to look at it again, to his amazement the lenses were perfectly clear, and he could avoid dismantling the scope altogether. Would that make sense to try in this case?

Richard, can I offer you a bit of advice before you embark on your telescope project. Feel free to ignore it of course, but it is based on long learned experience............. It seems to me that you have two ocular lens assemblies, both of which are enclosed in roll-sealed cages. Just be warned that as soon as you take these apart (more later), separate, clean and re-cement the lenses and re-house in the cages, then you will need to refocus the graticle and then the image because your action will have changed the focal and optical properties of the lenses because you have effectively changed the refractive index of the double lens .

The next thing is this.......... The FLINT part of the double lens configuration is VERY hard glass and will crack or chip, externally or internally as soon as you look at it!!!!!!! Worse still, it can 'scatter' internally caused by internal previously unseen fault lines within the glass. So treat the lenses as gold dust, made from the finest unobtanium mined in the mountains of Utopia.

On a personal note, I wouldn't re-pack into roll-sealed cages but I'd adapt the ocular lens system to mimic the No32 Mk1 free floating lenses, using spacers to take up any side or end float.

If, like you, I hadn't attempted such a job before, I'd get a couple of cheap old telescopes off ebay to practice on

But just be VERY careful

Peter:

Thanks for the advice. I only plan on repairing the rearmost lens. The inner lens still looks like new. Do you think that only repairing the outer lens will cause major problems?

My plan at the moment was to remove the roll over, remove the lens spacer ring, and then the lens VERY carefully. I have heard that alcohol will dissolve the old canadian balsam, but I certainly would like some advice on what / how to dissolve the old balsam.

I have some other old lens assemblies I can practice on with regards to dis-assembly and re-gluing for practice.

Richard

Quote:

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Originally Posted by Paul S.

Sniping In The Great War by Martin Pegler is a good book.

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...if you like books full of errors!

Regards
TonyE

My plan at the moment was to remove the roll over, remove the lens spacer ring, and then the lens VERY carefully. I have heard that alcohol will dissolve the old canadian balsam, but I certainly would like some advice on what / how to dissolve the old balsam.

I have some other old lens assemblies I can practice on with regards to dis-assembly and re-gluing for practice.
********************************************
The best I have found to dissolve Balsam is MEK (methyl ethyl ketone). You might be able to get a small amount from your local chemical supply house, otherwise you are stuck getting a 4 litre container. Nail polish remover (Boots Brand if in the UK) has sufficient amount of ketone that will also do the job, but it just takes longer. DON'T get in a hurry when soaking the lens couplet. It might take a week or longer, but longer soaking will save the lens from chipping if pried apart when not completely loose. The big problem is getting Canadian Balsam. It is now a hazardous product and my supplier cannot ship over one ounce (he now removes 1 ml from the bottle to make it under the ounce, and will now ship to me).
There are other products available to glue lenses but they are epoxy's and if you miss most are permanent so be warned.

"Canada balsam is soluble in benzene, chloroform, xylene, ether and ethanol." Also see Re-cementing doublet elements with Canadian balsam. However, I would seriously suggest try my non-destructive tip a few posts above. Terry Lee is the fortunate individual who stumbled upon this phenomenon, serindipitously.

I have separated about a million lenses over a bunsen flame. That's the way we used to separate microscope slides at school and optical lenses while I was an apprentice and out in the real world. Mark the edge with a pencil or a v shaped file mark then place on a gauze tray allowing just sufficient heat to allow the flint and crown to slide apart. Allow to cool. The balsam can be cleaned off in clean industrial methylated spirit. You're not so much interested in dissolving the old balsam as just cleaning it off!

I have only ever had one lens crack and that was a Scout Reg scope OG doublet that someone had re-cemented with UV-light cured non refractive index cement not realising that it SHOULD be separate but thinking that the cement had come apart. When I tried the heat, thinking that it was Canada Balsam, it wouldn't budge so I tried a bit more heat and it cracked internally. Luckily I had a load of them

In the Army, if lenses are UV cured, we write UV on the edges although I don't think that anyone re-cements lenses now. Maybe they ought to go back to the days of the No5 binos with a lens doublet cemented to a prism assembly! Phew........ that'd bring on the pains....

Thanks for all the information! The article that RobD mentioned is very informative. Seems this gentleman uses a light bulb to separate the lens!

RobD: Do you have any idea what solvent Terry Lee was using? Always worth a shot before moving to more dramatic steps.

Thanks everyone.

Richard

Richard, I've sent you a PM.
Rob

Is it just me - Does anyone else here feel a sense of foreboding about how Richards valuable lens assembly is going to end up........... Sorry Richard. I think it's time to let a local pro loose on your predicament.. The forum is only so good......

Peter: I have sent the scope off to several people here in the US that rebuild antique scopes - mostly Winchester A5's and Unertl's. They have all returned it saying that they do not wish to work on it. This is why I am now down to trying to repair the scope myself.

Here is Sunday's Update - I have the lens soaking in Xylene at the moment. I have made a detailed record by time with photos. So if anything good happens it will be fully documented. If Xylene does not work then Acetone will be tried as the next solvent.

On the other hand Richard, just do what lens makers and Instrument technicians have been doing since Canada Balsam was invented and gently heat it over a bunsen or gas flame. Sit it on a fork, about 6" above the flame and it WILL just slide apart, believe me. Or just boil it up in a pan - starting from cool. That's all the temperature that you need.

Or just send the thing here and I'll have it apart, cleaned, polished and re-cemented in 5 minutes flat!

Attachment 38074Attachment 38075Attachment 38074Attachment 38075

Peter:

I freely admit I have no idea what I am doing. If you are willing to repair the scope I am more than happy to send it to you.

I have started the Xylene experiement, and here are the initial before and current time results. Watching it since last night I did not believe that anything was really happening - just wishful thinking. Here are the startup and 0500 photos after soaking for about 8 and 1/2 hours.

Richard

Ask the usual sight repair suspects in Canada first (less freight and Customs hassle.....) and then speak to Brian at BDL. I'll have that finished in a couple of hours.

The thought of you (or anyone) peeling open caged roll-sealed lens cells fills me with trepidation. DO NOT DO IT, EVER, EVER. Anyone out there listening to me............ NEVER, NEVER but NEVER DO IT. Just mount the cell in a lathe and skim the roll part off. Best to sacrifice the rolled cell than the lenses. To un-roll the cell wall means levering your jemmy against the lens

So here is the result of my testing using a chemical bath in lieu of dis-assembling the lens. The results are not the equivalent of dis-assembling the lens and re-gluing them, but the scope is now usable until I can find someone to properly overhaul it.

If anyone is interested, I have a fully detailed time line with progressive photographs.

Impressive - can you post details of the method?

I will collate all the photos with the notes and post them this evening.

Richard

Thanks Richard, I'm definitely interested.

ATB

Here is the detailed report / timeline with photos on what I did the lens.

Richard

So do you conclude that the xylene/acetone dissolved and removed the balsam or rather "hydrated" it and made it diffuse evenly between the lenses again?

Did you file the slots in the lens retaining ring?

You can do the same thing when you heat the lenses. Just heat until balsam is fluid then gently rotate convex lens around in smallcircular movements to squeeze out the air and allow to set. Do again in 6 months. Only my experience I have to say.

My belief is that it did nothing to the xylene in the center of lens. I think the combination of the xylene and acetone removed the "crystalized" balsam at the edges of the lens. I also think that they provided a really good cleaning which makes the lens look much better. Although I have no emprical proof, I believe that someone in the past tried some type of repair to the lens without removing them from their mount. If you look closely at the photos you will see some specks of orange in the bottom of the bowl. I think this is part of the origianl crystalized balsam that was on the lens. I believe that there may have been some balsam on the exterior of the lens as well - again from some type of long ago repair.

As to the cuts in the brass, that was the work of one of the 'experts' I sent the scope to have it repaired. Instead of soaking the body in Kroil or some other penetrant, they filed the notches in the outer rim to use as wrench points to unscrew it. Then after 6 weeks they told me a) they couldn't fix it and b) they didn't want to try.

The scope has been out of the bath for about a week now, and I not seen any additional deterioration from the original photos.

I have given some thought to trying the heating method Peter was discussing above, probably using the light bulb technique as the heat source. Technically I believe it would work great, personally I am not sure I have the skill to do it without inflicting some type of damage, as the lens are still mounted.

Richard

This is getting as big as Ben Hur...... As a matter of interest Richard and others, you didn't REMOVE the crystaline structure of the balsam, you've just thinned it down for want of a better word...... but it's still there and it is there for good. That part of the balsam has broken down - that's why it looks like it does. It's like a lined face on the elderly lady next door. They can use all manner of this that and the other, creams, potions, magic formulas, oil of this and that but guess what...............

It's also like painting your living room but half way round, you find that the paint isn't going to last. So you thin it down a tad.......... then again ....... and again......... and again until you get to the last wall. And you can see straight through the 'new' but utterly useless layer pf paint. Just like the outer edges of the lenses only this time, while you can see through it, the old imperfections are still there, only covered up and what's more, there WILL be different optical aberrations. It's just a shame that you all haven't got a light transmission and reader to test this nonsense. THE BALSAM IS 80 YEARS OLD. IT HAS BROKEN DOWN. IT IS PAST IT'S SELL BY DATE. IT IS USELESS. That's why you'll have to do it again in 6 months, believe me

I know I keep droning on and on, but please............, and the remainder of you looking for a wonder cure or potions, creams and as-if-by-magic formulas can I just say, if you're doing the job, then please, take advice and JUST DO THE BLOODY JOB PROPERLY. Bodgybubba jobs were not part of my upbringing or training should not be a feature of this forum. There....................

And while I'm here and got it off my chest, I know I shouldn't say so, but there is some off-forum PM's doing the rounds that are what we politely call, taking the ........., er......... pi......, mickey out of all of the nonsense being put about

DPL,
Do you know of a source of supply for suitable Canada Balsam in the UK (I know there are more modern alternatives now, but CB is far more forgiving than the newer options)?

ATB

A note of advice for you do it yourselfers: Peter has repaired almost 250 scopes sent from my shop in the past 18 years not too mention countless ones while in the British Army. Some of the piles of crap I've sent including one that's on it's way back now wouldn't have made good fishing sinkers in the condition sent. The prices he charges for this rare service is peanuts or what I call "charity work". Be advised that he knows just a little bit about this stuff and y'all might want to take heed of his advice. Have a Happy Thanksgiving, (USA and anyone else who cares to celebrate). Brian

Thanks for those kind words Brian. It's not well known, but I don't actually enjoy doing them, I just do them for pocket money and the fact that I'd rather see them being out there being used. I can safely say that I don't ever remember bodging a job (unless it's on my sons car - which he always seems to want fixed by yesterday when it's outside in the rain or drizzle.....) But what I do want to do, is pass on the knowledge, detailed info, experience, know how and the hundred other hard learned bits and pieces. And all the time, doing so without the crap. I mean, as someone else has just mentioned sooooo accurately in a PM. 'Just how long can you keep using your 80 year old cooking oil before it spoils the chips...........?' I don't know the chemistry of it, but it does more accurately describe what I'm droning on about

Well, you know I've sent every No.32 or L1A1 scope plus a few PP Co. and others I've had through here except for a very few whether I thought they needed work or not. That way when someone purchased one of my rifles, they were always ready to go to the range. With your treasured long distance Armourer's course on the rifles and willingness to service the scopes, I think folks who've bought No.4T's and L42's from me over they years have gotten better than good value. Think about the 30 or so L42's I imported back in 2000. They were the last available in quantity anywhere and no one wanted them. I broke the bank to buy them all and without your help, many were unserviceable. Your help is always much appreciated! Keep up the good work.

This piqued my curiosity and I found this information on Canada Balsam: Canada balsam - Wikipedia, the free encyclopedia

It seems Xylene can be used as a solvent for CB.

I see it's used in Buckley's cough syrup too. I wonder what solvent they use to manipulate it!?:yikes:

We're going off at a tangent here Surpmil... Xylene ain't CB and it never will even be a substitute for it. It is one of the hundreds of thinning or solvents that can be used. All it's doing is thinning the already separated, old, skinned paint down. And when it's evaporated in 6 months, because it hasn't been mixed properly and allowed to de-gas, just as you all did in your school chemistry and bbasic biology lessons, guess what'll happen............

Best shot is to go and get some new paint!

I'm not arguing with your diagnosis Peter, just posting what I saw as most of it was news to me.

Regardless, kudos to the OP for trying and at least it's better than it was, if only for a while, and no harm done.

Incidentally, the one or two PPCo.s I took apart had no sealant around the eye lens retaining ring, have you ever found any there? I'm just wondering what would make that ring so hard to undo.

A suggestion for the OP: find a really tough piece of wood and turn a shallow hole in one end just a bit bigger than the retaining ring with a bottom corner that is bevelled or rounded, not square. Get a strong but thin piece of leather and drape it over the hole, push the ocular housing down into the hole over the leather, (pig skin or something non-slippery is best), grasp the leather over the wood in one hand (securing both together) and the ocular housing in the other and you may be able to turn out the ring. Make sure you're going in the right direction, and whatever you do, don't grasp the scope tube, only the housing. A bit of heat first wouldn't hurt.

What say you Peter, is there better way?

[QUOTE=Roger Payne;239477]I do reproductions & I'm currently waiting for the next batch to come in. I am also located in Sutton Coldfield just a stone's throw from you. Suggest you pm me if interested to take it further.
The serial engraved on the top of the mount is the rifle serial. The two large holes at each end of the flat are I am afraid post-War additions, but not a major pronblem. You are lacking the spacer & tensioning spring that fits along the one edge of the dovetail (where the two small screw holes are), but again, these can easily be made from a piece of spring steel.

You have a nice find Paul.

Hi Mr. Payne, Do you have PPCo. scope mount and bases to sell? Thanks.-

Hi Martelazzo. Drop me a PM & I'll have a look in the meantime. I had a few that came & went but am currently awaiting some more that are being made at the moment (both bases & rings), but I'll have a rummage about & see if I have anything left currently.

Best.

Roger.