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Thread: Opinions on a springer power increase

  1. #1
    Join Date
    Nov 2012
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    Opinions on a springer power increase

    Gents, I have a '73 HW35 (.177, leather piston seal) I've had for about 18 months. Originally doing 10.6fpe, but found to have an Ox spring. I fitted a standard spring and found t was doing 7.5fpe, after fitting a new breech seal. So, I did the breech leak fix advocated by Mick (T20). I also tried to fit a guide and top hat. However, the additional compression left the coil bound, so in a bit of a rush to take the rifle to the last bash, I assembled it without the top hat. Running at 10.3fpe at the bash, a twang was noticeable, so this weekend she came apart again and I took almost two coils from the spring before fitting the top hat and putting her back together. She's now settled in nicely and is doing 11.6fpe. Now the top hat lip was 2.5mm thick max and I removed 6.5mm of spring material, so I wasn't expecting to add to the power (in essence, I've decompressed the spring by 4mm) Or has the decompression, once cocked allowed the spring to release more efficiently? I'd welcome some opinions from people with more tuning experience than I.

    NB: the twang has now gone and it's just shot a short string over the chrono' with 4fps variance
    Last edited by CapitalBee; 19-10-2014 at 06:00 PM. Reason: NB added

  2. #2
    Join Date
    Aug 2009
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    Pontypridd
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    the piston acceleration is more suitable to the seals ability to create compression!

  3. #3
    Join Date
    Apr 2012
    Location
    Retford, Notts
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    34,748
    Yep,

    Sometimes, too much active spring. Quicker acceleration. Other dynamics not in harmony. TP choking? More piston bounce off the high pressure air cushion.

    Nice result, young sir. So now, quieter and smoother too?
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  4. #4
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    Tony, yes it is. I'll bring it with me to the bash again, along with the 35E

  5. #5
    Join Date
    May 2009
    Location
    Lairg
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    4,906
    I bunged an Ox spring in my Airsporter back in the old days & found it was a lot less powerful, pre chrono days so based on penetration of fence posts, splatology & the like. I put the original spring back in & it was fine again.
    After cleaning out all the swarf as the spring was eating the inside of the piston like nobodies business.

  6. #6
    Join Date
    Nov 2011
    Location
    Bexhill-On-Sea
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    5,436
    Quote Originally Posted by CapitalBee View Post
    Gents, I have a '73 HW35 (.177, leather piston seal) I've had for about 18 months. Originally doing 10.6fpe, but found to have an Ox spring. I fitted a standard spring and found t was doing 7.5fpe, after fitting a new breech seal. So, I did the breech leak fix advocated by Mick (T20). I also tried to fit a guide and top hat. However, the additional compression left the coil bound, so in a bit of a rush to take the rifle to the last bash, I assembled it without the top hat. Running at 10.3fpe at the bash, a twang was noticeable, so this weekend she came apart again and I took almost two coils from the spring before fitting the top hat and putting her back together. She's now settled in nicely and is doing 11.6fpe. Now the top hat lip was 2.5mm thick max and I removed 6.5mm of spring material, so I wasn't expecting to add to the power (in essence, I've decompressed the spring by 4mm) Or has the decompression, once cocked allowed the spring to release more efficiently? I'd welcome some opinions from people with more tuning experience than I.

    NB: the twang has now gone and it's just shot a short string over the chrono' with 4fps variance
    Top hat typically adds up to a ftlb, so you've found the right amount of spring matched with topper - the basic principal of a tune kit .......great result

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