POI changes between 2 shooters

Discussion in 'Long Range Hunting & Shooting' started by xarcher, Sep 12, 2017.

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  1. xarcher

    xarcher Active Member

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    Browning X Bolt Hells Canyon Speed in 300 WM. After going through the load development and getting under 1/2 MOA at 100 yards, I took the gun to my buddy's farm to see how it shot at 300 yards and beyond. So I set up a prone shooting setup on sandbags and I shoot a sub 1.5 inch group at 300 yards. Then I let my buddy shoot it and he lays down a 1.5 inch group at 300 yards, except his group is centered 4 inches from mine. (BTW, Parallax knob on the scope was set at 300.) So can someone explain the reason for different shooters having that much of a POI difference? I am talking about more than just saying "different shooter....different results". I accept that this can happen, it's just that I don't understand it.
    Thanks
     
  2. djfriesen

    djfriesen Active Member

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    When you say the parallax know was set, does that mean it was parallax free? I know the number on the dial doesn't always waste to zero parallax. If that was the case, it seems like that could be enough to account for the difference.

    Another possibility would be cant. Do you have a scope level, and did you both use it?

    Just thinking out loud here.
     
  3. J E Custom

    J E Custom Well-Known Member

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    Parallax is sometimes different for different shooters so It needs to be set by the current shooter. Head position is different and this alters the zero.

    I site in almost every rifle that I build to get the rifle close for them, but I tell each person that the zero needs to be verified by the owner before hunting because of the difference in shooters check well, position and parallax.

    As also stated, you or the other shooter could be canting differently, or simply holding or griping the rifle differently.

    This difference is the reason that "No One" should sight in someone else's rifle for them.

    J E CUSTOM
     
  4. Schnyd112

    Schnyd112 Well-Known Member

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    My dad and I cannot shoot the same zero on several rifles we own. The worst is his .300 wm. Zero for him is about 1.5" to the 5 o'clock of mine. We just look through it differently.

    On the same stroke I shoot a friends rifle fairly often and have not noticed any changes in zero.
     
  5. ShtrRdy

    ShtrRdy Well-Known Member

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    I notice a point of impact shift by shooting with a thick jacket on versus a T-shirt.
     
  6. Frank in the Laurels

    Frank in the Laurels Well-Known Member

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    It can be dramatic between individuals, just the angles that they look through the scope..between myself and my son depending on scope a couple of inches...put my wife in the mix and Lord knows what this might be... I have no explanation of why other than angles but it does exist and they shoot the same group size groups just in a different place..
     
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  7. J E Custom

    J E Custom Well-Known Member

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    I know lots of people know how to set/check parallax in a scope, but for those that are not sure maybe this will help.

    There are several types of parallax adjustments that need to be understood.

    The first is the objective lens adjustment located on the objective lens. It was the original method for adjusting to parallax free the scope. Parallax is present in all scopes even those scopes below 8x, even though they don't have enough to make a large difference at lower power, they still have some or they are adjusted at the factory for a certain distance only.

    The side focus/parallax is the newer method and it works differently and in conjunction with the focus.

    The reference numbers are not that dependable because of the shooter, and should be used for a reference only. The person/shooter needs to verify the parallax for him self. also some side focus types of parallax adjustment must be returned to zero and advanced until Parallax is removed. If you go past the Parallax free condition you should return to zero and advance back to the best location.

    There are many ways to adjust parallax but the easiest way I have found is to set the rifle on some kind of rest that prevents the rifle from moving easily. then after you have determined the distance you want the scope to be parallax free, set it to what you think is correct but do a final check by placing your head in the shooting position without touching the rifle and place the reticle on the target at the desired distance. While not touching/moving the rifle bob you head up and down about 1/2 inch looking through the scope. If there is still parallax the reticle will move up and down on the Point of aim indicating the presence of parallax. Windage is effected the same, so when parallax
    is removed from the vertical it will be removed from the horizontal at the same rate.

    The worse the parallax, the more the point of impact will move based on the shooters head position.

    Hope this helps some

    J E CUSTOM
     
  8. phorwath

    phorwath Well-Known Member

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    My son's POI is most normally different than mine.

    He knows how to adjust parallax and so do I.

    I think the cause is he holds the rifle differently than I do. Different resistance to recoil. Different rifle motion as trigger breaks?

    Some hypotheses on my part. What is certain, is that his POI is normally left of mine at 300 yes. Enough so that scope turret adjustment is required.

    So as J E stated, I only complete a rough sight in for his rifle. He has to perform the final zero.
     
  9. coop2564

    coop2564 Well-Known Member

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    This is very normal as others have said. Each holding different pressures and places change vibrations. Also same reason why you should not sight in using sled or bi-pod unless thats how you plan to hunt. Further the distance further off it will be.
     
  10. xarcher

    xarcher Active Member

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    Thanks guys for all of the feedback. What this also does is emphasize the need to be consistent in one's shooting routine. Appreciate all the comments.

    JE, also thanks for the advice on how to check whether the dialed parallax is for real. I have moved my head up and down and left and right to validate it, but I had always assumed that the dialed in adjustment was accurate.

    Just another thing to keep me up at night wondering.........
     
  11. lancetkenyon

    lancetkenyon Well-Known Member

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    Cheek weld, shoulder.positioning, shooting position, recoil absorption, difference in facial features and positioning, eye differences, cant, grip, trigger pull, etc.
     
  12. phorwath

    phorwath Well-Known Member

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    Exactly. And probably more that we're unaware of.
     
  13. 117LBS

    117LBS New Member

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    Lots of help here. My dad and I have always shot to different points of impact on about every rifle.
     
  14. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Had this yesterday while working with a very high end scope that I will be writing a review for. Had rifle set up on a gong at 670y where I was hitting the dot. Let two different buddies shoot and they both hit about a foot higher than I. They had a two shot group about 2". Only thing I could come up with was I free recoil the rifle and thus it was riding the bags differently.

    Steve