HW97K tuning

Discussion in 'Piston & Spring' started by scraggoak, Jun 11, 2019.

  1. scraggoak

    scraggoak New Member

    Joined:
    May 25, 2019
    Messages:
    4
    Location:
    Correze France
    I have owned a HW97kt for about a year and lost interested due to poor accuracy. So i decided to try to improve the performance, Having read many posts on Air Rifle tuning i purchassed a Chrono and a Vortek tuning kit from Tony Burton, before stripping the gun i chronographed it and calculated the output power at 11.6ftlb and the Velocity was fairly constant. I striped the rifle which was full of grease, cleaned all the parts Polished the compression tube inside and out then fitted the new kit and as instructed used a small amount grease on the piston seal skirt. The kit came with two spacers, i only fitted one and once assembled the output power was 15.7ftlb so i stripped it again and removed the spacer then re assembled the rifle. The ouput power is now 13.9ftlb after putting around three hundred pellets through it. On the plus side using a 14.6gn pellet i am getting reasonable groups with no flyers, I have emailed Tony and asked how i can reduce the power below the legal limit, I would appreciate your suggestions and opinions on how to reduce the power without cutting the spring down. Cheers Geoff
     
  2. Nick G

    Nick G Active Member

    Joined:
    Nov 21, 2012
    Messages:
    442
    Location:
    coventry
    Club:
    Greyhound/ Purley Chase
    You will need to cut the spring to bring it down by that amount, or if it has a piston weight in , remove it & see how you get on.
     
  3. scraggoak

    scraggoak New Member

    Joined:
    May 25, 2019
    Messages:
    4
    Location:
    Correze France
    Hi Nick thanks for your reply, What would you consider to be reasonable amount to cut,

    I have been advised not to talk about a gun that is above the legal limit on a forum, and thanks for the advise, but i live in SW france where the limit is 14ftlb I just feel that it might be a little more accurate below 12ftlb
     
    Last edited: Jun 11, 2019
    Ash Bailey likes this.
  4. Nick G

    Nick G Active Member

    Joined:
    Nov 21, 2012
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    442
    Location:
    coventry
    Club:
    Greyhound/ Purley Chase
    Its going to be a case of one coil at a time , and test in between I am afraid
     
  5. imorik

    imorik Member

    Joined:
    Oct 24, 2009
    Messages:
    184
    Location:
    Azat-le-Ris, France
    Club:
    Ex Anston FTC
    Had a 97 some years ago and fitted a vortek kit. Was instantly transformed, less recoil and accurate. Was doing 13.5 ft lb :eek:. Reduced power down to 11.5 ft lb and was worse recoil wise and less accurate :(. 97's with 26mm internals were designed for power levels above UK limit ;).
     
  6. Nick G

    Nick G Active Member

    Joined:
    Nov 21, 2012
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    442
    Location:
    coventry
    Club:
    Greyhound/ Purley Chase
    That's why I convert them to 22mm comp tube ;)
     
    imorik likes this.
  7. scraggoak

    scraggoak New Member

    Joined:
    May 25, 2019
    Messages:
    4
    Location:
    Correze France
    Hi all
    This afternoon i decided to strip the rifle down and maybe use the original hw spring with the vortek spring guide and piston seal, i soon had the rifle apart removed the spring had a close look at the spring tube and found the original steel spacer washer stuck inside, managed to remove it re assembled the rifle put a few pellets over the chrono and the power was a healthy 11.8ftlb so problem solved, Will check the accuracy tomorrow.
    Thanks for all your input Regards Geoff
     
    Last edited: Jun 12, 2019
    Gary Martin likes this.

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