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Thread: JSB pellets - Problem with accuracy

  1. #61
    Sharp Shooter
    WP HFT/Springer Champ '16

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    Lots of good advice here, my HW97's are my favourite.

    Glad to see some better groupings, the JSB Express can be a bit unpredictable at times, especially if there is a bit of wind.
    Most of the 97 fan club around here prefer the 8.44's

    As Riaan says, come and join us for a shoot, next one is at Wetton in January.
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  2. #62
    Sharp Shooter
    WP HFT/Open Champ '16
    WP HFT/Springer Champ '17
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    Hi Scope

    Have a look at the HFT session on the Forum, we shot our last league for the year but will go at it again in January, if you are looking for some fun shooting I will probably be going to Kraaifontein Shooting range in December, we can meet up there.

    All my my friends are going to Betty'sbaai, Gansbaai, Tietiesbaai... I am just going on "stand baai".


    Quote Originally Posted by Scope View Post
    @Gertfrik, thanks for the advice.

    RiaanduToit, I know what you mean about twangy! I was expecting a much smoother sound from the legendary Weihrauch HW97K, but being my first I had nothing to compare it to. Mine seems to still be dieseling a bit, when I shoot it there is that definite diesel smell in the air and sometimes when I open the pellet port there is a wisp of smoke after a shot. Is this normal? And how long does it continue like that for?

    The pellet isnt going supersonic or anything, but theres definitely a grey mist residue on my shooting rest after an hour of shooting. I dont know if this is normal and something others experience?

    Some articles Ive found online say that an air rifle MUST diesel and that its normal and part of the design. Other things Ive read say dieseling is a big no no.

    The tuning sounds really interesting and something I would definitely explore in the future.

    Where do you guys shoot? I would like to come and have a go shooting and learning from some more experienced people.
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  3. #63
    Marksman

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    Hahaha "stand baai"

    thats absolutely classic Gertfrik! Sorry for the slow reply - been hectic with year end and work.

    I would love to come and join you for some shooting, Im away with family over Christmas/New Year. But Im definitely keen to come through in January
    @AndyT, Gertfrik and Riaan - thanks for the invites guys
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  4. #64
    Marksman

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    Quote Originally Posted by Scope View Post
    @Gertfrik, thanks for the advice.

    RiaanduToit, I know what you mean about twangy! I was expecting a much smoother sound from the legendary Weihrauch HW97K, but being my first I had nothing to compare it to. Mine seems to still be dieseling a bit, when I shoot it there is that definite diesel smell in the air and sometimes when I open the pellet port there is a wisp of smoke after a shot. Is this normal? And how long does it continue like that for?

    The pellet isnt going supersonic or anything, but theres definitely a grey mist residue on my shooting rest after an hour of shooting. I dont know if this is normal and something others experience?

    Some articles Ive found online say that an air rifle MUST diesel and that its normal and part of the design. Other things Ive read say dieseling is a big no no.

    The tuning sounds really interesting and something I would definitely explore in the future.

    Where do you guys shoot? I would like to come and have a go shooting and learning from some more experienced people.
    If your air rifle is still dieseling like you say then you will have to clean the barrel fairly regularly to get consistent accuracy. My guess is that you should be cleaning the barrel quite frequently, certainly a lot more than you might like to, until the dieseling stops to get the accuracy you're after.
    Last edited by Sisuphos; 13-12-19 at 21:43.
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  5. #65
    Marksman

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    Although I shoot .22 PCP I have had a few batches of 18.13 JSB that were not well finished and gave bad groups
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  6. #66
    Sharp Shooter
    The Professor

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    Quote Originally Posted by Scope View Post
    Some articles I've found online say that an air rifle MUST diesel and that its normal and part of the design. Other things I've read say dieseling is a big no no.

    First off with the so called dieseling, this can occur in two ways, you can get either a gentle combustion, or a much more violent event that can, in extreme cases, cause damage.

    I think the theory that some combustion of lubricant is required stems back to experiments by the late Gerald Cardew - author of the book The Airgun From Trigger To Muzzle, latterly re-issued as The Airgun From Trigger To Target.

    In his experiments he showed that the test rig he used gave greater power when some lube was burned in the firing cycle.

    However, subsequent development indicates that certain peculiarities of his test rig made this a necessity, whereas other combinations of piston stroke length and bore size negated the need for combustion to boost power.

    Overall I would lean to saying that with modern designs any combustion is not beneficial to performance and will mess up seals over time.

    Some manufacturers can be quite generous with their lubrication and some of this inevitably gets into the compression chamber and burns off.

    My own preference is to strip and clean a new rifle thoroughly, check for any other issues, remediate if required and re-assemble using appropriate lubrication - both type and quantity.

    I would suggest with your HW97 it would be worth stripping it to give it such a clean and re-lube.

    I favour using a combustion resistant lube for the piston seal, my favourite currently being krytox grease and a very high moly content paste applied sparingly to the spring and guides.

    The better fitting the spring guides are the less lube is needed, using a heavy grease to remove spring 'twang' is masking a problem not curing it.
    Last edited by Dale; 16-12-19 at 10:12.
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  7. #67
    Sharp Shooter
    The Professor

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    Quote Originally Posted by Sisuphos View Post
    If your air rifle is still dieseling like you say then you will have to clean the barrel fairly regularly to get consistent accuracy. My guess is that you should be cleaning the barrel quite frequently, certainly a lot more than you might like to, until the dieseling stops to get the accuracy you're after.
    As in my reply to the OP above, rather cure the cause of the problem than just tolerating it.
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