Interesting POI Shift

Discussion in 'General Airgun Chat' started by Ash Bailey, Sep 12, 2019.

  1. Ash Bailey

    Ash Bailey Grumpy old sod!

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    A new TX200 with H&N .177 8.64 gn pellets.

    Front (left) hand rested on a bean-bag, open-palmed. Butt pad into the right shoulder, ten shots at 20 yards, pellet on pellet, or sub 10mm group. At the time wearing a padded jacket.

    Remove said jacket, same process, same size group about 10-12mm higher than that with my jacket on! Just a T-Shirt between me and the rifle.

    I wasn't holding the rifle too hard into my shoulder.

    Interesting to see - explanations welcome! :confused:
     
  2. Lavant_Lad

    Lavant_Lad Old Git.

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    Thats a springer for you, they have a mind of their own.:)
     
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  3. Nomads HFT

    Nomads HFT Well-Known Member

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    Two possibilities spring to mind, Ash. First is that the rifle is pushing into the elastic muscle of your shoulder during recoil, creating potential energy that subsequently adds a little push to the surge from below the axis of the piston, tilting the rifle slightly further back.

    Second is more amusing - you are suffering from butt slippage when wearing your T-shirt.
     
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  4. gc93

    gc93 New Member

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    I get a difference in poa when wearing jumper jacket or tshirt with standing shots, with a jacket on I think it stiffens the shooting position up and t shirt "im less held" and the poa is 2 clicks right and I click up. maybe in your case the recoil is absorbed a little different so your poa moves slightly
     
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  5. tillygti6

    tillygti6 Tilly's gun stocks

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    For me, it's possible the guns now sitting lower on your shoulder and closer to your body.so your cheeks also now on the slightly lower part of the cheek. Your likely getting a small bit of Px error. Your looking lower through the scope the shots landing higher.
     
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  6. Ash Bailey

    Ash Bailey Grumpy old sod!

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    Thanks guys for your insight.

    Sometimes shooting becomes a science, or artform, or both.

    I'll try again in a week or two to see if the same happens with another springer.

    Jim... I do try to avoid butt slippage :(
     
  7. Wheelieneilie

    Wheelieneilie Active Member

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    I noticed the same. I got rid of it by adding 6mm thick self adhesive neoprene to the curved end of the bisley rubber butt pad that I use and now have 6mm of softer give. I have to renew it every 6 months or so as it compresses over time otherwise my groups open up slightly.
    ATB Neil
     
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  8. Ballisticboy

    Ballisticboy Active Member

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    It is all part of shooting of any kind being a system, in this case the system is the pellet, the gun and the shooter. Modify any one of the components and it will potentially change the POI of the projectile. It is the same with tank guns and artillery and anything else which fires a projectile. For example in the case of the tank or artillery modify the suspension, the wheels or the recoil system and you will change the POI. So change your clothing and you may well change the recoil and potentially change the POI.
     
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  9. MickyFinn

    MickyFinn I❤HFT

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    Ash, i get poi shift with the springer between stubble & clean shaven. Also experienced poi shift with a jacket change. There's a reason why the pros like Steve Whiting always wear the same jacket come rain or shine!
     
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  10. Slip Stream

    Slip Stream Experienced novice

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    I always wear the same clothing when shooting I.e.skeet vest,shirt,trousers and T-shirt.
    And my POI. is all over the place, must admit by the end of summer the pellet seems really fly faster ?
    Maybe i should wash them once in a while !:confused:
     
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  11. skeet_200

    skeet_200 New Member

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    If you haven't already, I suggest that you check where your reticule finishes in relation to the target, after taking the shot. If it gravitates to to a different point, depending on whether you're wearing a jacket or not, this may provide an indication of the souce of the error.
     
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  12. Nomads HFT

    Nomads HFT Well-Known Member

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    Hold sensitivity.jpg

    Here's the effect on the recoil cycle, showing pellet exit, of shooting a rifle that's free to recoil, and one held lightly against the shoulder muscle. A padded shooting jacket vs tee-shirt will not be as marked as this, but the principle is the same - the rifle will be pointing in a different direction at pellet exit.

    Ash - if you bring your jacket to Nomads we can test the recoil with and without.
     
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  13. FPoole

    FPoole Active Member

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    I've always found my TX groups better with a sweat shirt of light jacket on. The problem is, I just can't keep the jacket on as the weather warms to the 90's f.
     
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