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Thread: I'm Sat Waiting On Postman Pat

  1. #46
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    Quote Originally Posted by T 20 View Post
    As far as I can make out, Tone, they're the same stroke as the HW50, so about 65mm, which would tie in with John Walther's Airgun book which tells of a HW55 model that used a HW50 cylinder and barrel latch ?

    Hopefully I can stretch the stroke to around 72mm but I may be able to go a little more, it's very difficult to give an exact figure until I've measured everything up a few times.
    I can't work measurements from the HW50 I have in bits as I have a 99 barrel on that which moves the cocking lever about 3mm forwards of it's normal position.

    All the best Mick
    How long has your stroke ended up Mick? I seem to remember that you bad some breech void issues?

    I have a mild case of the flu, so been tested for covid, and not allowed to leave the house for some days until the test comes back...

    Which means I have some time to work on the old rusty HW50s!
    I had an extra piston, and has machined it down as much as I dare, plus added a steel seal converter so the piston can take Diana/AA seals.
    Had to lengthen the cocking clearance in the piston a few mm's and the stroke is now somewhere between 73-74mm.
    Put in a brass tophat from another HW50 project, and a ARH/JM E3200 spring.

    The gun behaves quite well during firing, but I have no idea how fast it shoots, as the chrono in in a box somewhere...
    Too many airguns!

  2. #47
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    Quote Originally Posted by evert View Post
    How long has your stroke ended up Mick? I seem to remember that you bad some breech void issues?

    I have a mild case of the flu, so been tested for covid, and not allowed to leave the house for some days until the test comes back...

    Which means I have some time to work on the old rusty HW50s!
    I had an extra piston, and has machined it down as much as I dare, plus added a steel seal converter so the piston can take Diana/AA seals.
    Had to lengthen the cocking clearance in the piston a few mm's and the stroke is now somewhere between 73-74mm.
    Put in a brass tophat from another HW50 project, and a ARH/JM E3200 spring.

    The gun behaves quite well during firing, but I have no idea how fast it shoots, as the chrono in in a box somewhere...
    Hi Evert.

    By coincidence I looked at jumping back on this on Monday and ran the action over the chrono, it's only running at 520fps so I'll be going back in to her pretty soon so I'll measure the stroke for you.

    I'm thinking now that I could have lightened the piston too much or I could need more weight and a different Spring, as luck would have it I found a couple of new Titan springs in the pile which will fit the piston at 18.35 mm OD.




    All the best Mick

  3. #48
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    Quote Originally Posted by evert View Post
    How long has your stroke ended up Mick?

    Had to lengthen the cocking clearance in the piston a few mm's and the stroke is now somewhere between 73-74mm.
    .
    Ah, Evert.

    Embarrassingly, and weirdly, after a quick measure I only seem to have a 66.5mm stroke. --- I thought I was over 71mm.

    I'll double check in the morning and strip the action down again but it looks like I'll have to machine up a custom piston.
    Alternatively, perhaps I could use a 99 piston and just replace the body with a 25mm one, depending on the 99 piston's length.



    All the best Mick

  4. #49
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    Quote Originally Posted by T 20 View Post
    Ah, Evert.

    Embarrassingly, and weirdly, after a quick measure I only seem to have a 66.5mm stroke. --- I thought I was over 71mm.

    I'll double check in the morning and strip the action down again but it looks like I'll have to machine up a custom piston.
    Alternatively, perhaps I could use a 99 piston and just replace the body with a 25mm one, depending on the 99 piston's length.



    All the best Mick
    If my memory is correct, its been stated somewhere that the HW55 has been delivered with different pistons adapted to different power level.
    May just be a rumor though, or me remembering something that was said about another gun.
    Too many airguns!

  5. #50
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    Quote Originally Posted by evert View Post
    If my memory is correct, its been stated somewhere that the HW55 has been delivered with different pistons adapted to different power level.
    May just be a rumor though, or me remembering something that was said about another gun.
    I'll definitely be stripping the HW50 action down in the morning as something doesn't add up here after reading this thread :-

    https://www.airgunbbs.com/showthread...15#post7990915



    Perhaps I measured it wrong this afternoon, though I don't think I did --- very weird.

  6. #51
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    Quote Originally Posted by T 20 View Post
    I'll definitely be stripping the HW50 action down in the morning as something doesn't add up here after reading this thread :-

    https://www.airgunbbs.com/showthread...15#post7990915



    Perhaps I measured it wrong this afternoon, though I don't think I did --- very weird.
    I did measure this wrongly.

    After stripping the action this morning I found the stroke to be 69.45mm, this ties in with my prediction of the stroke in the above link, which I missed yesterday.

    I will try to have a measuring session over the weekend and then work out the design for a new piston, though it could be that I could extend the stroke on the piston I have.




    All the best Mick

  7. #52
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    Quote Originally Posted by T 20 View Post
    I did measure this wrongly.

    After stripping the action this morning I found the stroke to be 69.45mm, this ties in with my prediction of the stroke in the above link, which I missed yesterday.

    I will try to have a measuring session over the weekend and then work out the design for a new piston, though it could be that I could extend the stroke on the piston I have.




    All the best Mick
    The stroke is somewhat limited by the cylinder in itself. I think you may be able to reach 75mm, but not much more.
    And you may probably reach those 75mm's by just trimming the front of the piston.
    I'm a bit afraid to take too much off and have the piston coming apart during cocking.
    Too many airguns!

  8. #53
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    Quote Originally Posted by evert View Post
    The stroke is somewhat limited by the cylinder in itself. I think you may be able to reach 75mm, but not much more.
    And you may probably reach those 75mm's by just trimming the front of the piston.
    I'm a bit afraid to take too much off and have the piston coming apart during cocking.
    As I started out with a 65mm stroke piston my machining for the TX piston seal is now within 0.5mm of the cross pin hole, so machining the piston face back any further is a none starter strength wise, Evert.

    I'm pretty confident that altering a 99 piston could be my best bet --- but if someone could tell me the overall length of a HW99 piston I'd know for sure ?




    All the best Mick

  9. #54
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    Quote Originally Posted by T 20 View Post
    As I started out with a 65mm stroke piston my machining for the TX piston seal is now within 0.5mm of the cross pin hole, so machining the piston face back any further is a none starter strength wise, Evert.

    I'm pretty confident that altering a 99 piston could be my best bet --- but if someone could tell me the overall length of a HW99 piston I'd know for sure ?




    All the best Mick
    I havent seen any cross pin hole
    Looks to me like it was brazed toghether.
    Too many airguns!

  10. #55
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    Quote Originally Posted by evert View Post
    I havent seen any cross pin hole
    Looks to me like it was brazed toghether.
    My HW55's piston has a cross pin.

  11. #56
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    Quote Originally Posted by evert View Post
    I havent seen any cross pin hole
    Looks to me like it was brazed toghether.
    My 50 piston has both cross pin and brazing :-

    image.jpg

  12. #57
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    Threaded interchangeable piston heads and shallow piston seals would assist with piston stroke length in Mk1 Hw50's

    Rather time consuming though but something to consider if you have the time and skill to do it

  13. #58
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    Quote Originally Posted by HW55T View Post
    Threaded interchangeable piston heads and shallow piston seals would assist with piston stroke length in Mk1 Hw50's

    Rather time consuming though but something to consider if you have the time and skill to do it
    Hi John

    If my calculation of the HW99 piston length being 146mm overall, then by machining the Weihrauch piston seal arbor off to expose the piston rod, I could thread the rod to use interchangeable piston heads.
    By doing this I could easily alter the stroke between 71mm up to 76mm.

    The other alternative I've been looking at is using a TX200 latch rod in a homemade piston body, I could then simply increse the stroke by screwing the rod further into the body --- I'd need to alter the Rekord top sear to use the TX rod but that's a simple enough operation.

    Something else I need to have a Squint at is the possibility of using the piston I've already altered but extending the stroke by moving the Rekord pin holes backwards in the back block.
    This would increase the stroke and also give a setback trigger, but I have a feeling there's not enough room in the block to do it.




    All the best Mick

  14. #59
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    Quote Originally Posted by T 20 View Post
    I must admit there's still a couple on my wish list, Paul.

    I wouldn't mind a Pro Elite and a HR93 in the collection, but I'm not that fussed if I don't get either.
    If i ever come to a bash i will bring my elite and rh93 for you to play with. Rh93 is in a nice factory thumbhole stock to

  15. #60
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    Quote Originally Posted by T 20 View Post

    Something else I need to have a squint at is the possibility of using the piston I've already altered but extending the stroke by moving the Rekord pin holes backwards in the back block.
    This would increase the stroke and also give a setback trigger, but I have a feeling there's not enough room in the block to do it.

    All the best Mick

    Wow! Now that is extreme thinking out of the box. Guessing, like you say, that there may not be enough room to allow this, but you never know.........
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- Spring / Summer 2022...BOING!!

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