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Thread: A tricky problem!

  1. #1
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    A tricky problem!

    This concerns what on the face of it looks an excellent rifle. It is an early 25mm HW77 which has has a new spring, spring guide and top hat installed by a very experienced tuner with an excellent reputation at my club. Shooting a 10 shot string over my chrono gave a reasonable-although in fairness not fantastic- consistency showing a MV between 734 and 753 ft sec with a large cluster between 746 and 753 fps.. Honestly I don't suspect the power plant because in my view the variation in MV does not explain the 9" group of 10 shots over 30 metres which this rifle produced in a random spread during a wind free spell earlier today. In addition the group ranged from left to right as well as up and down.
    I have taken the gun apart and checked the following:
    The piston seal-excellent condition. looks unworn.
    The spring-has polished ends and the guide and top hap fit perfectly.
    (Really for the sake of it I have changed the spring/guide/top hat and the results are the same.) I really do not suspect the power plant.
    The scope-changed several times, no improvement.

    What can be wrong? Before you answer, please bear in mind that I am not clueless on spring rifles and whilst not a great shot, I do understand how springers work and usually can shoot them pretty well. In any event a 9" group is well below my usual standard even on a bad day!
    Thanks for reading.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  2. #2
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    What does the bore and crown look like?
    The OAKS
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  3. #3
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    Was it OK before the new parts ?

    Check the obvious like stock screws & breach seal first.

  4. #4
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    Quote Originally Posted by si7777777 View Post
    What does the bore and crown look like?
    Crown looks fine. Bore not easy to check as it is a fixed barrel rifle. Next job to do.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  5. #5
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    Quote Originally Posted by landymick View Post
    Was it OK before the new parts ?

    Check the obvious like stock screws & breach seal first.
    Honestly I don't know as the rifle came to me with them fitted. However what would have to be the problem with what looks like a well finished spring and properly fitted guides to give me such terrible groups?
    Stock screws properly tightened and breech seal looks fine.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  6. #6
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    Quote Originally Posted by Rapidnick View Post
    Honestly I don't know as the rifle came to me with them fitted. However what would have to be the problem with what looks like a well finished spring and properly fitted guides to give me such terrible groups?
    Stock screws properly tightened and breech seal looks fine.
    Hi Nick

    Just to narrow the fault down - is it the same shotgun spread with a selection of pellets - makes and head size?

    Cheers Steve

  7. #7
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    There must be an issue inside the barrel which is forming the pellets into a lopsided shape.

    One little rust spot could do this I guess?

    Matty
    Opportunity is missed by most people, because it is dressed in overalls and looks like work.

  8. #8
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    Quote Originally Posted by Weasle View Post
    Hi Nick

    Just to narrow the fault down - is it the same shotgun spread with a selection of pellets - makes and head size?

    Cheers Steve
    We have spoken. I think you are on the right track-recrowning is probably the answer.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  9. #9
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    Quote Originally Posted by MattyBoy View Post
    There must be an issue inside the barrel which is forming the pellets into a lopsided shape.

    One little rust spot could do this I guess?

    Matty
    Agreed-see my reply to Weasle.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  10. #10
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    Is it possible for the breach block to contact the pellet skirt & deform it ?

    Can you speak to the person who did the work ? he might remember the rifle having an issue from the off.

  11. #11
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    I would strip the guts out clean the bore and push a pellet through it and see what I can find .
    Even at 20 fps variation impact point should be negligible , shine a light down the bore and cotton bud the crown .

  12. #12
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    Barrel imperfection taking a chunk out of the pellet, or re-crown. Damaging a crown only takes a pull through

  13. #13
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    for it to be that bad...

    with the rifle stripped, try pushing a pellet through it very carefully, see if you feel anything odd...
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  14. #14
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    Thanks to everyone who has contributed. I'll revert after further testing.
    'It may be that your sole purpose in life is to serve as a warning to others'.

  15. #15
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    Nick

    It’s the crown, barrel or pilot error in that order.

    If it’s a .22 bring it to Kempton and I will recrown it while you wait, it’s a five minute job with the right tool.

    Rich
    A man can always use more alcohol, tobacco and firearms.

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