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Thread: The Webley Mercury pistol project: Part 3, and the last!

  1. #1
    ccdjg is offline Airgun Alchemist, Collector and Scribe
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    The Webley Mercury pistol project: Part 3, and the last!

    It has been a while since my last post, but I have now managed to finish my Webley Mercury pistol project, and for those of you who have been following the ups and downs of my efforts, here is a brief account of how things went.
    The following pics show the second model prototype gun that I was trying to copy on the left, with my pistol on the right, as it stood at the end of Part 2.

    http://www.airgunbbs.com/showthread....hlight=Mercury







    There was obviously the need for front and rear sights, chequered walnut grips and a safety catch, as well as appropriate etched lettering and an overall black finish.

    The strategy I chose to make the front sight unit was the simplest I could think of that was within my limited capabilities, and was certainly not the one used for the original pistol. But it gave the right cosmetic effect so I was happy with it. It is summarised in the following set of pictures. I broke it down into two parts - the “ramp” and the hood.




    As shown in picture (A), a section of steel plate was used to make the ramp, and it was first grooved along one edge for most of its length; a section of steel tubing for the hood was slotted to mate tightly with this, as shown in (B). The base of the ramp was then milled to give a stepped section, and a recess was milled into the end of the barrel to accept this, as shown in (C).

    Having got the ramp to be a nice snug fit in the barrel recess, I then shaped the ramp it and filed a sight blade at its top, as shown in (D). The ramp was then soldered in place (E) and the hood slid in place, as in (F). The hood, which can only slide forwards, is essential for making cocking a pain-free experience, and although it was a very tight fit, it could easily be removed if needed, by a sharp tap with a piece of wood.

    The rear sight unit, as shown in the last pictures of the sequence, was an easier project, as the Mercury prototype used a standard Webley Hurricane sight, and I able to purchase one of these off the forum. It needed a slight radius on the underside to make it fit closely to the cylinder, and after drilling and tapping the cylinder it was firmly attached with two 4BA screws. On the original prototype there was a curved block in front of the rear sight assembly, which was there purely for cosmetic reasons.. Pictures (G) and (H) above show how the block was constructed, with a hollow interior to cover the piston guide screw, and picture (I) shows it fixed in place in front of the sight.


    After the sights were completed, the next phase of the project was to make the wooden grip plates. On the original prototype, the grips were made of walnut, chequered, and the left-hand plate had a pronounced thumb rest with a recess for a safety catch lever. The sequence of events I followed in making the grip plates is summarised in the next group of pictures.




    Two flat sections of walnut were cut from a larger block, as shown in (A). One of the sections was cut thicker to allow for the thumb rest. I always think you get a much better looking result with wood grips if you can arrange for the grain and figuring to follow the rake of the grip, so I made sure of this as best I could. The grip outlines were cut out with a hacksaw. The profiling for the thumb rest I found I could do most easily in the lathe, using an end mill for removing wood and with the grip plate clamped to a rotary table, as shown in (B). Picture (C) shows the left-hand grip with thumb rest after further finishing with a file and emery paper. The grips were drilled for the securing screws. The left grip also needed to have a recess let into it to accommodate the safety catch lever, and this was achieved again by milling. Then came the part I like the least – chequering. It is not something that I am good at, and I have to take it very slowly. The plates were screwed to a heavy block of wood to keep them steady while the chequering was being done, as in (D), and after what seemed a lifetime, the results were as shown in (E). Not particularly professional but adequate I think. The plates were then finished with satin polyurethane varnish, applied in very thin layers with rubbing down with finest steel wool between each coat. The final result is shown in (F), and you can see what I mean about the grain following the angle of the grip.

    The safety catch was the last mechanical part of the gun that needed to be tackled, and the construction of this is shown in the next picture sequence. The first version of the Mercury pistol had no safety catch, whereas the Resuggan version clearly did, as indicated by the safety catch lever on the left hand side of the grip. If you study the patent drawings (which depict the first version only) there was no such safety shown. So I had no clue as to how Resuggan’s safety catch worked, but I was able to work out something functional from the location of the catch lever. All it required was an off-set pin on the lever pivot that intercepted the sear lever in the “safe” position and prevented it moving. An anticlockwise turn of about 20 degrees was sufficient to rotate the pin out of engagement with the sear and leave it free to be released by pressure from the trigger. The resultant safety catch unit was made in two parts as shown in the first two pictures, and the third picture shows it in place on the grip. Although very simple in construction, I found that the safety worked remarkably well in practice, so I imagine that this must be very similar to the design that Resuggan used. When the lever is in the down position the gun is ready to fire. In the up, or “safe”, position the gun cannot be cocked. Or if it has already been cocked then it cannot be fired.




    With all the functional parts of the gun now complete, I was able to assemble the pistol in its rough state, fit it with a reasonably strong main spring, and then test fire it. To my relief everything worked perfectly – much better than I expected, as usually there is a lot of fettling to do with a new build. The detent broke smoothly and the spring-loaded pawl on the cocking lever made a loud click as it engaged with the first notch in the piston. Pushing against the spring, the barrel could be swung down until another loud click indicated that the sear had engaged with its notch in the cylinder. Returning the barrel home gave another loud click as the pawl engaged briefly with the second piston notch, and once the barrel was closed the gun was then cocked in the low power setting and ready to fire. To get higher power the whole sequence was repeated, needing more effort this time of course, and a similar sequence of clicks could be heard. I found the clicks to be reassuring, as it showed that everything was engaging properly and there was unlikely to be any surprise slippages or premature firing when cocking.

    I then shot 30 or so pellets through the gun, at both power settings, with no problems whatsoever, and then suddenly, just as I was feeling smug that I had everything under control, the gun misfired at full cock. The problem persisted intermittently, and to make matters worse, sometimes the cocking pawl would slip its notch during cocking, especially on the second full power stroke, which was not good for the nerves. I had visions of the sear and/or pawl having worn or sheared, or the notches in the piston having chipped off due to faulty case-hardening. Or it could be down to my own poor engineering skills and poor tolerances.

    Eventually I found out the cause of the problem. It seemed that as the gun was being fired repeatedly, the rear screw that held the grip frame and cylinder together slowly unscrewed. This enabled the cylinder to lift a minuscule amount from the grip as the gun was being cocked, so that there was reduced contact between the cocking pawl and the sear and their respective notches in the piston. When the tension got to a certain level, slippage occurred.
    To solve the problem, the grip-frame fixing screw was fitted with a keeper screw to prevent it turning, as shown in the following picture. Once this had been fitted, I had no more problems, and I have since put several hundred shots through the pistol, even with powerful springs fitted, and the gun has worked perfectly so far (touch wood).




    Now that the gun was up and working it was time to think about the final finishing touches – the lettering and the bluing. I wanted the lettering to describe accurately what the pistol was, also making it clear that it was a reproduction. The following picture above shows the final etching result (taken after the gun had been blued). As is usual, I also etched my signature, date and place in an inconspicuous part of the gun, in this case on the heel of the grip.






    The next stage was to colour the metalwork of the pistol, and all the relevant steel components were blued by the hot salt method which I have used successfully before on other projects. This went well and a 10 minute immersion in the bluing bath at 140 deg C gave the result shown in (A) of the next picture sequence:




    The side plates for the frame were aluminium and so needed a different approach. One option would be to use a black lacquer of some sort, but this somehow did not appeal to me. Also the original Mercury prototypes, which were almost entirely made of aluminium alloy, appeared to have been chemically blacked rather than painted. With aluminium and its alloys the most popular way of achieving a chemically generated coloured layer is by anodising and dyeing, and this is most probably what was used on such iconic air pistols as the Walther LP53 and the Feinwerkbau. The result is a hard, scratch and corrosion resistant layer, which retains much of the character of the underlying metal. I had previously had a go at anodising in my previous project, the Haenel LP55R pistol, but in that case the anodising layer was not dyed and a silver effect was obtained. This time I would need to take the aluminium parts straight out of the anodising bath and into a black dyebath. Once the dye had been absorbed to give the depth of black I wanted, the surface would then be permanently sealed by boiling the parts in water.
    Picture (B) shows the plates coming out of the dyebath, and (C) shows how the plates looked after sealing in boiling water. They were an excellent match for the blued steel frame shown in (A).


    With all the finishing completed I could now assemble the gun. The following pictures show the final result:







    A box was made up with a veneered plywood top and bottom and hardwood sides, avoiding joints by fixing the whole thing together with PVA glue. After a bit of staining and applying two thin coats of polyurethane clear satin varnish, the box looked OK.




    The interior was fitted out with green baize and foam rubber. A mint, period tin of Webley pellets, courtesy of Troubledshooter, together with a manual, a few targets and a couple of implements completed the picture.


    So the pistol was now complete, and it was as close enough in outer appearance and mechanical operation to the original Mercury to make me happy, but the question remained, how would it perform? The first, and most important thing to decide was the best spring, or combination of springs, to use as the power source. The patent drawings show that a double spring system was used. Presumably the springs were pre-compressed slightly in the cylinder, but there was no way of knowing to what extent.
    I had available three suitable springs of different sizes and strength as shown here.




    The larger spring had an outside diameter of 19 mm, and the other two springs fitted easily inside it without any binding. The wire diameters of the springs, which give a rough indication spring strength, were 2.5, 2.0 and 1.5 mm.

    The muzzle velocities and energies were measured by chrono’ for different spring combinations, using unsized .177 waisted pellets (Diana flat heads), each weighing 0.505 g. Measurements were averaged over a string of 10 shots, and the consistency was reasonable, at about plus or minus 10-15 fps.
    The first set of tests were the lowest in power, the gun being fitted with the wide spring (A) only. At the single-stroke setting the gun registered 180 fps, and this increased to 315 fps for two strokes.

    The spring power was then upped by using a combination of springs (A) and (C). There was a noticeable increase in the effort needed to cock the gun, but even the second stroke was still very easy to do because the double cocking action uses a shorter cocking stroke than conventional break-barrel pistols. With this spring combination, the lower power setting gave an average muzzle velocity of 233 fps and the higher setting a very respectable value of 385 fps. The lower figure compares with a value of 287 fps claimed by Webley for their Junior pistol, and the value of 385 fps compares very favourably with the factory quoted values of 350 fps for the Premier, 416 fps for the Senior, and 420 fps for the Hurricane. I think one can safely assume that the factory quoted values are going to be for highly optimised conditions.The Mercury was noticeably more comfortable to double-cock than the single-stroke any of these, but of course the two strokes took slightly longer to carry out.


    Finally a combination of spings (A) and (B) was used, and now cocking required an uncomfortable increase in effort for the second stroke. Surprisingly at the single-stroke level, the muzzle velocity was practically the same as with the the weaker spring combination (A) plus (C), and a velocity of only about 220 fps was recorded. However, at the second stroke level, the velocity did increase markedly, up to 440 fps (about 3.5 foot pounds). However, in my opinion, the gain in muzzle velocity was not worth the increased effort of cocking, and I found the (A) plus (C) combination infinitely preferable.
    So I decided to used the (A) plus (C) spring combination for accuracy testing.


    The following picture shows the target from a string of 10 shots, with the gun charged at the two-stroke level, shot from 6 yards and using a bench clamp. As you can see, all 10 shots fell in an area about the size of a 20 p coin, and in fact the spread horizontally was much less than that. The vertical spread being larger than the horizontal spead was probably due to a very small upward creep of the pistol in its clamp after each cocking, as it the pattern did seem to proceed upwards as the number of shots increased. I was very pleased to see that there were no flyers. At the top of the picture are examples of the same type of pellet, fired at the same power level, point blank at a steel plate.

    When a second accuracy test was caried out under identical conditions, but using the single-stroke power setting, a similar tight grouping of 10 shots was obtained, again with no outlyers.




    So having put several hundred pellets through the gun at various power levels, what are my conclusions?

    On the downside, my gun is heavy at 1.7 kilos, which compares with 1.5 kilos for the BSA Scorpion and 1.9 kilos for the Milbro Cougar. However, the original Mercury prototypes would have been much lighter, as they were constructed largely of aluminium alloy, whereas mine was mainly steel. Another downside that was not obvious at first, and was a peculiarity of the double cocking principle, was that once the gun had been cocked to the higher power level it was not possible to de-cock it completely, and it could only be de-cocked to the lower power level. Any attempt to de-cock a second time resulted in the start of a second cocking stroke. Once the lower power level had been reached, the only way of making the gun safe was to fire it. This caught me out once, when I had forgotten I had cocked the gun to full power and after de-cocking I was under the impression the gun was safe. So I was carrying around a cocked and loaded gun without being aware of it. A surprise firing when I pulled the trigger (with no disastrous consequences I am glad to say) made sure that it never happened again. I can see that this aspect of the gun’s design would not be something that would recommend it to the market!


    The gun has some definite positives, most significantly the ease and comfortableness of cocking compared to pistols of similar power. Another aspect that I liked was its versality when using it for general plinking. For most purposes the lower power setting was adequate, and cocking was effortless. However, when fancying a few longer range shots, or wanting to do real damage to a can, the instant availability of the higher power setting was a nice thing to have.


    All in all, it was a difficult project (mainly due to problems of my own making) and took longer than expected, but I am glad that I undertook it. Not only did it help while away the hours of lockdown, but I now have a gun that looks good in my collection, one that is a working copy of a model that I would never be able to own, and it has also helped answer a few technical questions about an obsolete design. Equally important, I have a gun that is very enjoyable to shoot, and I am sure it will get quite a bit of use.
    Last edited by ccdjg; 03-10-2020 at 09:11 AM.

  2. #2
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    Thank you for posting such an informative thread, John.
    The end product looks superb and well worth all the patience, effort and skill you put into it.

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    That is an amazing build!
    Thank you for sharing this with us, your work is inspiring!

  4. #4
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    Great work!
    I enjoyed your write ups
    Wonder how it would have been received if Webley had put it into production

  5. #5
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    A damn fine read! Thank you, I enjoyed every minute of it. I'm blown away by the high quality of your workmanship. Apart from the decocking issue, it looks like a commercial winner. This version looks much better than the other prototype, the non-target Mercury, because the sweep of the shroud below the barrel plus the rearsight ramp gave the disconcerting impression of a barrel that pointed upwards!

    Vintage Airguns Gallery
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    In British slang an anorak is a person who has a very strong interest in niche subjects.

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    Wow

    That, if I may say so, is hugely impressive, well done that man👏
    J.
    ok, I admit it, I've got a problem.
    [url]http://www.rivington-riflemen.uk/[url]

  7. #7
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    I am so very, very impressed, but that out of date pellet tin spoils it for me. please make some more . kind regards Al

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    An artisans hands and a scientific mind. you are a very talented man sir. Congratulations on your achievement . It looks simply wonderful and from reading the test results, you have achieved what you aimed for.

    respect.

  9. #9
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    Also v impressed with your workmanship, in metal & wood, let alone your thoughts and logic in problem solving.
    Sympathetic metal work teacher was lientent to using facilities to make bits for motorcycles and Airguns, These bits got me an apprenticeship with Rolls Royce, withdrawn 2 months before due to start when RR went bust in 1971, still itching to improvise, adapt and remanufacturer after 50 odd yrs in the commercial field.

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    Quite extraordinary and very impressive.

    Trying to get my head round why you can’t de-cock all the way from full.

  11. #11
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    Quote Originally Posted by cringe View Post
    I am so very, very impressed, but that out of date pellet tin spoils it for me. please make some more . kind regards Al
    What pellet tin would you suggest as being more appropriate ?

  12. #12
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    Astounding work well done.
    Morally flawed

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    Quote Originally Posted by Troubledshooter View Post
    What pellet tin would you suggest as being more appropriate ?
    Given the time period at which the pistol was developed and the fact that the rectangular pellet tins were obsolete almost 15 years before, would a more contemporary tin such as the round, green , black and white tin not be more appropriate for the period?

    I agree with cringe in that the pellet tin looks incongruous when cased with the pistol.
    Last edited by WebleyWombler; 23-09-2020 at 07:32 PM. Reason: Got the .177 colour wrong

  14. #14
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    Fantastic to see. You are truly a talented man.

  15. #15
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    Quote Originally Posted by ccdjg View Post
    ....
    Now that the gun was up and working it was time to think about the final finishing touches – the lettering and the bluing. I wanted the lettering to describe accurately what the pistol was, also making it clear that it was a reproduction. The following picture above shows the final etching result (taken after the gun had been blued). As is usual, I also etched my signature, date and place in an inconspicuous part of the gun, in this case on the heel of the grip.





    The lettering looks really good! Can you tell us more about your etching technique? Are you using stencils?
    Last edited by evert; 24-09-2020 at 07:11 AM.

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