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A quick POI homework assignment

Discussion in 'Shooting Related Threads' started by Neil Winston, Dec 18, 2009.

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  1. Neil Winston

    Neil Winston Well-Known Member

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    You test your gun and it shoots 10 inches high and straight (right & left) at 40 yards, You know that gravity causes anything to fall four inches in the 0.14 seconds it takes your shot to get from the muzzle to the target.

    You cant the gun 90 degrees to the left so it's lying on its side.

    Aiming in the same place, where does it shoot now, and why?

    Neil
     
  2. Jim101

    Jim101 Active Member

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    14 inches left and 4 inches low. Gravity only works on the verticle component. You have to add the 4 inches of drop to the 10 inch POI with the gun rotated 90 degrees. You also have to include the 4 inch drop in the new verticle POI.




    Close as a country boy can figure it out. Jim
     
  3. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    I hafta guess it would shoot 10 inches to the left and low since the bead is now half way down the side of the barrel, bore wise and pattern height wise. Why? Because rotating the centerline of the bore 90 degrees, the bores angle has changed from an up slant to directly sideways which nullifies the vertical elevation prior.

    HapOwly?:)
     
  4. crusha

    crusha TS Member

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    I'll go with Jim's answer, too.
     
  5. SMITH47

    SMITH47 Member

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    i'm still workin on the lazer test ??

    ernie
     
  6. Smiley

    Smiley Member

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    By turning it to the left it will shoot 14 inches left as the rib is on the left side and was 10 high inches in the o/u position and it will shoot 4 low as gravity takes over as per Neil's thread.To throw something into the mix no one has said anything about side by side shotguns,how does the poi change when the barrels are placed in a vertical plane?
     
  7. JACK

    JACK Well-Known Member Supporting Vendor

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    Yah-ah. I'll test it out today and report back
     
  8. Neil Winston

    Neil Winston Well-Known Member

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    I'm going to go with Jim 101, Buzz, and Smiley: over 14 and down 4. They used the same reasoning that made sense to me, but I'm sure we all remain open to a better argument even it it leads to different numbers and will require us to change our minds.

    In the interest of full disclosure, I have to say that what was for you all a math/logic diversion was for me a "penetration test," another pedigreed shotgun-testing pastime from the early days of the British periodical "The Field." What had been the impact of my recent "Cant and high Rib" test? I'm glad to see that no one said the result of the above depended on the rib height; my message must have not only breached the hide and caused the interior tissue damage we all witnessed, but apparently emerged on the other side in virtually pristine condition. That tells me the evening I spent in the shop doing it was well invested.

    Neil
     
  9. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    SS, why does a field shotgun with no rib print patterns at 50/50??

    "4 inches low because you lose the vertical component with no rib."

    Approx 4 inches of drop is measured from the bores centerline at 40 yards, not what's on top of the barrel. Very easy to prove with bore peep sights, a deprimed 12 and 20 ga. hull.

    Hap
     
  10. fishguts

    fishguts Member

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    This is a hard one, but I'm workin' on it.

    .14 X 10"/speed of light+40 yards(x.14/34")+6:10am = uhh,uhh...wait.

    Wayne
     
  11. phirel

    phirel TS Member

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    Seems rather simple to me if one remembers that gravity pulls things straight down. Over 14 inches and down 4 inches.

    When the gun was vertical, it really shot 14 inches high but gravity took away 4 inches. On its side it will shoot 14 inches to the left and gravity will pull in down 4 inches.

    Nice thought Neil. Now, if we integrate this answer into the gun cant question, it can get complicated.

    Pat Ireland
     
  12. g7777777

    g7777777 TS Supporters TS Supporters

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    OK I will go with 14 and 4

    Gene
     
  13. Jawhawker

    Jawhawker TS Member

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    Seems rather simple to me if one remembers that gravity pulls things straight down.

    Then how comes when levitating an object, it is not subjected to the forces?
     
  14. wayneo

    wayneo Active Member

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    +1 for Jim101, interesting article I've included. Wayne
     
  15. zzt

    zzt Well-Known Member

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    +2 for country boy Jim101. He got it right.
     
  16. Shooter R

    Shooter R Active Member

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    To put it in practical terms... If testing does "prove" 14" Left and 4" low...(Disreguarding the slight drop), If you cant a gun at 45 degrees, it would be 7 inches left, if your gun is canted 22.5 degrees, which most wold agree is quite extreme, your only off by 3.5". With less cant there doesn't seem to be much effect on P.O.I.
     
  17. short shucker

    short shucker TS Member

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    I need more coffee in the am before opening one of Neil's threads.

    ss
     
  18. wayneo

    wayneo Active Member

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    Ding, ding, ding..... round 2
     
  19. phirel

    phirel TS Member

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    Work on this one. The top barrel of my O/U shoots 12 inches high at 40 yards and the bottom barrel shoots 9 inches high at 40. If I cant the gun at 45 degrees , where would the barrels shoot?

    Pat Ireland
     
  20. Neil Winston

    Neil Winston Well-Known Member

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    Oh darn, wayneo, here's I am on my stool in my Everlast trunks and freshly-pressed robe - and he's a no-show. . .

    Neil
     
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