Bullet drop formula?

Discussion in 'Weapons / Marksmanship' started by Frisco, Mar 31, 2011.

  1. Frisco

    Frisco Weapons free Member

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    I've been searching for like an hour online and I can't find a formula to calculate bullet drop.

    I don't need tables, I'm doing it for an assignment for my trig class so I have to do the math myself.
    Any ideas? I think I've calculated all the actual data I need, I just don't know exactly how to put it together.. Thanks.
  2. JAB

    JAB Infantry Verified Military

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  3. Marauder06

    Marauder06 Intel Enabler Administrator

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    Isn't there an iPod app for that?
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  4. x SF med

    x SF med Special Forces Moderating Staff

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    It's a slope formula with the added distractors of velocity, gravity, time - it could be even more complicated with spin and wind over distance. It's a 4 dimensional slope equation. Remember before there is drop there is rise (ballistic jump) so you have a parabolic/ballistic slope.
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  5. Marauder06

    Marauder06 Intel Enabler Administrator

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    :eek:
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  6. Frisco

    Frisco Weapons free Member

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    I figured out the drop with a perfectly flat trajectory, the ballistic jump is where I'm having trouble I don't know how to factor it in. I've got the effects of wind, spin drift, and the coriolis effect calculated, so I will factor those in once I find the drop...
  7. SgtUSMC8541

    SgtUSMC8541 Marine Scout Sniper Verified Sniper

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    [​IMG]
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  8. Frisco

    Frisco Weapons free Member

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    If you calculated it for a prefectly flat trajectory out of the muzzle it would work if your barrell was exactly level with your scope.. IE your reticle is perfectly parallel to your barrell to begin with.. The parabolic slope only comes into effect if your already sighted in at a given distance.. right?
  9. x SF med

    x SF med Special Forces Moderating Staff

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    You need to calculate the 'vacuum parabola' from muzzle to the crossing point of the 'flat trajectory' if you figure poa/poi is essentilly flat at 100m, you can interpolate the rise by using 150m drop as being the height of rise at 50m (high point for ease of calculation (friction/velocity change/spin change/gravity actually pull the high point back toward the muzzle - but using center of flat is close enough) . This changes slightly with barrel angle for drop at greater ranges. Remember as the projectile loses energy/velocity/spin, the effect of gravity increases.

    Think a long tailed student's t distribution or a long tailed z distribution as the basic shape, the steep slope of the curve being the terminal side of the ballistic projection.
  10. Mac_NZ

    Mac_NZ Stitch Bitch Verified Military

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    Who are you and what have you done with the Troll?
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  11. JAB

    JAB Infantry Verified Military

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    Damn old man, where in the hell did all that come from? I would hate to read your data book…. lol:eek:
  12. x SF med

    x SF med Special Forces Moderating Staff

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    sometimes you actually have to do the math because you don't have the charts or a fancy computer.

    I didn't get into charge versus projectile weight calculations and how that changes the actual initial parabola from muzzle, did I? You guys always forget I was an 11B/18B before I got better and became a medic. I still like making boomsticks do their magic.
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  13. Crusader74

    Crusader74 Verified Military Verified Military

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    Does that change during extreme weather? Ie Rain or Hot Weather? I remember a rd rises in rain and drops in hot weather..
  14. x SF med

    x SF med Special Forces Moderating Staff

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    any significant change in Barometric mmhg will effect the round/ballistics. Rain - lower poressure, more friction and the possibility of minor deflections. hot weather lower friction, higher pressure.

    Most of that is internal calculus... better known as Kentucky windage.
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  15. Chopstick

    Chopstick Verified Estrogen Brigade Member

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    XSF is really Stephen Hawking???:confused:
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  16. x SF med

    x SF med Special Forces Moderating Staff

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    I have warned all of you not to be fooled by my Trollish figure... there is more to me than meets the eye... one of these days you will believe me. Until then, beware. I may surprise yet again.
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  17. Marauder06

    Marauder06 Intel Enabler Administrator

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    Math? Math can be sexy(2nd from right)...

    sexy math.jpg
  18. policemedic

    policemedic Verified Military

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    This thread just satisfied my daily learn-something-new requirement. Times 12.
  19. Freefalling

    Freefalling Signal Administrator

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    This thread made my brain hurt.
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  20. SgtUSMC8541

    SgtUSMC8541 Marine Scout Sniper Verified Sniper

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    Its shit like this that made us invent Nerds to make calculators. Oh, and BDC's.
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