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Thread: HW97K POI shift

  1. #1
    Sharp Shooter

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    Default HW97K POI shift

    Anyone with HW97K experience. Had mine for a few months and as expected is capable of shooting good groups. However a strange phenomena has emerged resulting in a impact shift. Stable for about 3 tight (5 shot) groups before changing pont of impact (normally in a clocwise pattern with groups shifting up to about 6 mm for another few groups before shifing again). Investigated scope/mounts, operator inconsistencies (hold/trigger control), stock/action mounting screw tightening torque variationd and pellet alternatives, to no avail. On removing the stock I have now found the main "U" shaped mounting bracket fixing (via 2 screws) the fore-end of the stock to the rifle itself, to be completely loose (as in rattle fit, capable of moving at least 1mm from side to side). There are two adjacent, externally visible, welds at the barrel receiver interface that I presume should fix this bracket in place.

    Is there anybody who can confirm original fixing condition of this bracket and shed some light on the problem. Thanks.




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  2. #2
    Marksman
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    Vernon I will post your query on the BBS for you...
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  3. #3
    Marksman
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  4. #4
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    Hi Vernon

    The bracket moves on mine too. Don't know if they supposed to or not tho.
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  5. #5
    Sharp Shooter

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    Thanks Guido and DD. Will also check replies on BBS.
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  6. #6
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    I am pretty sure that it is because of velocity changes ie. velocity inconsistency. I am pretty sure that you dont have a Tune Kit in your gun and that if you put it over a chronograph it will show velocity deviations.IMO if you want accuracy then your gun should not regurarly hace 10fps deviation with a max of 15fps. If it is velocity related (go and test it over 30 shots one after another) then you should get a Maccari or other decent kit (spring,spring guide, lube and a new seal.
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  7. #7
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    Vernon, the mounting bracket is supposed to be loose, dont worry about that. Do you clean the barrel? I have heard of this phenomena before. Dieseling could be a cause. Do you smell smoke after a few shots? It could be that there is a bit of oil on the piston seal or even in the barrel. This could accelerate the pellets inconsistently, and cause variations in mussel velocity.
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  8. #8
    Sharp Shooter

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    Have not cleaned the barrel as yet but will do so. Do get a slight burning smell from time to time. Surely velocity inconsistencies will show up from shot to shot to produce erratic groups. Groups stay consistent but just shift around after every third group or so. Strange/frustrating one this.
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  9. #9
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    And what scope do you have mounted?
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  10. #10
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    Yes, i had the same symptoms with my springer before the tune kit. the gun would fire great for awhile then move poi, i dont know exactly why it happens but it seems to me that maybe the gun heats up by the first coupleof shots and then starts to diesel? test it over a chrono
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  11. #11
    Sharp Shooter

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    Leapers 8-32 (2 piece Leapers mounts with locating pin) used with 97K. Tried the 10-50 Lynx from my S400 which gave the same results.
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  12. #12
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    Vernon, I agree with Airking, put it through a chronograph test and see if the mussel velocity is constant. How many shots have you put through it so far?
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  13. #13
    Sharp Shooter

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    Probably about 800 - 1000 shots so far.
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  14. #14
    Marksman
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    I do not think it can be the muzzle velocity...it would cause the occasional flier but not the whole group to shift.

    It has to be something to do with the front stock screws , inletting, etc...perhaps even shooter input???
    Ihad the same problem with an Hw90

    Jokes aside but try giving the rifle to someone else to shoot and see what happens
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  15. #15
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    I have just e-mailed Weihrauch in Germany to see their response. Guido, I think you may be right..... for the whole group to shift like that indicates that either the sight or barrel is moving. The holding bracket and front stock screws secures very firmly on my rifle when tightened properly. It literally pulls tight when you fasten the screws. I doubt that has anything to do with it.
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