same weight/ same POI ?

Discussion in 'Reloading' started by Mada, Mar 7, 2012.

  1. Mada

    Mada Well-Known Member

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    I read somewhere in my Hornady manual v8 that bullets with the same weight or design (i cbf to find and site) will fly the same?

    has anybody heard of or know of such?

    -Derrick
     
  2. justgoto

    justgoto Well-Known Member

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    There is a lot more to it than bullet "weight or design;" I can get the POI to be much different using the same bullet with differing velocity.
     

  3. MTBULLET

    MTBULLET Well-Known Member

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    where did you find that in the manual ?
     
  4. Mada

    Mada Well-Known Member

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    I cant find it :/ im just imagining things now
     
  5. Trickymissfit

    Trickymissfit Well-Known Member

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    weight has nothing to do with it. Bullets with the same ballistic coefficient and the same velocity will have the same trajectory. Just because they weigh the same does not mean they have the same B/C.
    gary
     
  6. rscott5028

    rscott5028 Well-Known Member

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    And, because they have the same BC, doesn't mean they weigh the same. Or, that they are necessarily even the same caliber.
     
  7. Mada

    Mada Well-Known Member

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    lets say we have two cartridges. same velocity, identical everything, except the bullet. the bullets weigh the same but the difference in BC is 0.075
    is it possible to achieve the same zero at 100yrds?
     
  8. rscott5028

    rscott5028 Well-Known Member

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    You can establish a 100yd zero with any and all rifles.

    But, the trajectory at varying distances and the windage compensation will always be different unless they at least have the same BC and same MV.

    .075 is not a huge difference. So, it all depends on how exact you want them to be.

    You can take a lower BC bullet and shoot it a little faster to keep the trajectory similar to the higher BC bullet. But, it's not going to be identical beyond some distance.

    -- richard
     
  9. Trickymissfit

    Trickymissfit Well-Known Member

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    they will not have the same trajectory or flight path if everything is identical otherwise. In this case it won't be very much at all, but they still will be different. There is an algerbraic equation to plot this that figures in gravitational pull and velocity plus the other stuff, but it's easier to plot it out with a PC program if it will allow you go go three or four places in the B/C.
    gary
     
  10. Bart B

    Bart B Well-Known Member

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    I doubt anyone could tell the difference between two bullets whose BC varies by 20% at 100 yards. At 200 yards, it will start to show.

    What the heck does "i cbf to find and site" mean? I hope you're not using smart phone "texting" language on this web site. I don't have a dictionary to find out what all those abbreviations mean. And, if you are, I think it's very presumptious on your part that all of us know that impersonal communication language.
     
  11. Mada

    Mada Well-Known Member

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    CBF just means "cant be bothered" or "cant be f**k" sorry, its a web term, assumed you guys knew what it means.. again sorry
     
  12. Mada

    Mada Well-Known Member

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    Thanks alot for all of your explanations, much thanks
     
  13. justgoto

    justgoto Well-Known Member

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    I shoot a Hornady 150gr FMJ and a Hornady 150gr SST in the same rifle. The charge weight is .5grains different, the BC is .017 different; the POI difference is less than moa at 400 yards.

    So I practice with the FMJs that are 2/3s the price of the SSTs.
     
  14. Mikecr

    Mikecr Well-Known Member

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    Another qualifier to the question is changes to seated ogive distance to lands -w/resp to a gun's personality. This, because tune greatly affects POI.
    And going from a tangent ogive to secant for example, all else equal, can have a big affect on POI and performance in general until optimum seating is again determined.

    I can't imagine changing bullets, even lot to lot of the same, without seeing some difference.