Huben K1 Review And Insight Into Accuracy Problems

Forums PCP Airguns Huben K1 Review And Insight Into Accuracy Problems

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    Gregor
    Participant
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    Sorry, wrong link…

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    peole
    Participant
    Member

    Tanks, Gregor.
     yes it does look very mild and rifling starts pretty much immidiately. Which is ok, I’d guess for bolt action that slowly pushes pellet in to barrel.

    Huben slams pellet in to barrel at full force – same as revolver bullet goes at maximum psi. 

    Here are pics of revolver cone – you cant miss it:)

    http://www.google.com/search?sclient=tablet-gws&client=safari&hl=en&q=revolver+forcing+cone&oq=revolver+forcing+cone

    Also, I think now I understand why Huben does not recommend to replace barrel – clearance between barrel and magazine is critical. So I think before tightening 3 barrel screws one needs to use thickness gauge to set the gap. 

    Revolver gap is 0.02mm. My guess on air rifle it can be even less cause theres no danger of burned powder buildip that causes magazine jams on powder burners.

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    jgburks
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    I wonder how an FX Smooth Twist barrel would fare in the Huben? There wouldn’t be any rifling to slam the pellet into at least. Maybe Gregor can fit one of those as well.

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    peole
    Participant
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    “jgburks”I wonder how an FX Smooth Twist barrel would fare in the Huben? There wouldn’t be any rifling to slam the pellet into at least. Maybe Gregor can fit one of those as well.

    i think that will be to obvious:) but … FX have similar problems (just not so laudly discussed)

    
FX impact skirt damage

    FX impact spiraling and fix:

     

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    Gregor
    Participant
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    Hi guys, sorry for late response…
    Yes, it is quite complex to change the barrel on Huben K1. Actually it is easy to replace it but complex to adjust it in the correct position. You have to be careful how far in you thread it and you also have to alight it axially with the magazine. But it is not impossible and you do not need any special tools to axially alight the barrel.
    I have tried to shoot pellets in water and did no see any damage on them, so I guess the cone is ok…
    The gap between the barrel and magazine is not critical though, because of the clever design that Huben uses: Back side of the magazine (where the air blows in) is sealed with a plastic seal with an o-ring. This seal is pushed forward by the pressure when a shoot is taken and pressed against the magazine to make a seal. At the same time this plastic seal pushes the whole magazine forward and the magazine presses against the barrel to make the front seal. There is no air escaping felt when firing (and this is a bullpup so I would notice it on my neck…)
    I am sure that smooth twist barrels are great for standard lighter pellets but I don’t think they would work well with heavier pellets / slugs because of their non-aggressive twist rate, but if someone would be willing to send me one of those barrels, I would be happy to put it in and test it. :)
    We are working with Rojal (http://www.rojal.si/en/) to offer a custom barrel for Huben or better yet Huben with already built in custom barrel. You can find both products here:
    http://www.rojal.si/en/shop/airguns/airgun-addons/huben-improved-barrel-5-5.html
    http://www.rojal.si/en/shop/airguns/air-rifles/huben-k1-preorder.html

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    Steyr
    Participant
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    hi gregor. is this barrel a straight swap – i.e. will the shroud still fit? any videos regarding accuracy?

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    Gregor
    Participant
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    Hi. Yes, the barrel is straight swap and the shroud will still fit. I do not have a video for the custom barrel yet, but you can see my group on Rojal web page at 50 meters…

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    dunsai
    Participant
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    Gregor
    very good videos. 
    i was just wondering if there was any change in accuracy between the first barrel installed in the video and the new Rojal barrel. 
    Thanks

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    dunsai
    Participant
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    Hi Gregor,
    could you please post a video with the new custom barrel using different pellet weights, lengths and velocities and is this barrel made with 1 : 16″ twist or different twist rate.
    thank you

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    Gregor
    Participant
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    I will try to make this video in the future (probably not to an extend that you would like with different twist rates because it takes some time to change the barrels) …

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    Gregor
    Participant
    Member

    Hey guys.

    I am designing a new bullet mold for Huben.

    Please check out this thread if you are interested:
    /topic/a-custom-bullet-mold-for-huben-k1/

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    skorec
    Participant
    Member

    Whats about to test  “Shilen select match barrel .22 Caliber 1-8 Twist”   ? 

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    Gregor
    Participant
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    If someone is willing to send it to me, I would be happy to try it out :)
    Generally these barrels have a little bigger diameter and therefore need a bigger slug that will not fit in the magazine. Also 1-8″ twist will significantly reduce velocity and is also not needed for such short projectiles. Ant the last part: I assume you has in mind to use copper plated bullets that will have too big friction… Remember: airguns have limited pressures.
    Just yesterday I wanted to test some 120 grain bullets in my wolverine 303 with 7,65 barrel. It is regulated to 150 bar (I get about over 100 ft-lbs with jsb pellets) and the bullet got stuck in the middle od the barrel :(

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    skorec
    Participant
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    Sorry for mistake. They offer also  1-14  but little bigger diameter is really the problem.
    I do not want to believe that nobody produce 5,5mm air rifle  barrels whit faster twist (1-12 …… 1-15 ). Also polygonal rifling will be better ?   
     

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    Gregor
    Participant
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    Despite what people believe, polygonal does not bring any significant higher velocity in airguns. They do bring higher velocity with firearms but not because the friction is lower but because they are tighter and higher pressure builds up behind a bullet before it enters the rifling… I have tested this in .30 cal (Wolverine303) and the velocities were almost the same with both barrels…

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    Gregor
    Participant
    Member

    Hi.

    I had some success with the mold project. Check the thread if you are interested:
    https://www.airgunnation.com/topic/a-custom-bullet-mold-for-huben-k1/page/3/

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    vvalerio80
    Participant
    Member

    I purchased my 25 cal from Kelly at Crazycool in the states. It is in perfect functioning condition. I have put through over 200 rounds so far. Just an FYI it can not be filled with a hand pump unless it’s the Huben one.  It needs more pressure right from the start. A compressor or tank will be your best friend. 

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