Bullet Drop

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Thread: Bullet Drop

  1. #1
    Senior Member Array Timmy Jimmy's Avatar
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    Bullet Drop

    How far out will a .45 ACP bullet in 230 gr stay flat and at what range will it start to drop and then how fast will it drop?

    If these are the wrong technical terms to use please educate me!
    Timmy Jimmy

    If it is not in the US Constitution then the Federal Government should not be doing it.

    "Carrying a gun is a social responsibility."

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  3. #2
    Member Array Randy's Avatar
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    The bullet starts to drop as soon as it leaves the barrel.

    In order for the bullet to hit a target at some distance, the barrel must be angled upward relative to the line of sight when the bullet departs. It's like throwing rocks at a tin can. You have to throw 'over' the intended target in order to hit it because, once you release the rock, gravity starts pulling it towards the ground.

    Here are two graphs - the first one shows the bullet's path given the barrel was horizontal when fired (the term for this is "drop") and the second one shows the bullet's path when passing through a known 'zero' point at 25 yards distant.

    The load used in this model is Remington's R45AP7. It has a 230gr JHP bullet (BC .162) at 835ft/sec. Atmospheric conditions are 'standard'.





    Randy

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    Member Array Flippinstk's Avatar
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    Timmy Jimmy,

    US NAVY Firecontrol solution answer..... (laymans terms)

    - A fired projectile will drop at the same rate and impact the ground as a non-fired projectile as long as the fired projectile does NOT have any elevation correction or hit anything in its path.

    -No matter what the caliber, size or powder charge, gravity acts the same on all projectiles.

    -Hold a firearm perfectly horizontal.
    Hold the same size projectile even with the end of that barrel at the same height.
    The instant the fied projectile clears the barrel the held projectile is dropped.
    Both projectiles WILL hit the ground at the same time.

    Inject a zero gravity, zero atmospheric condition or a elevation adjustment and the outcome will change.

    Its a simple process actually.... gravity works!
    Alex G.
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    Senior Chief Petty Officer, RETIRED, USN
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    Member Array craze's Avatar
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    Quote Originally Posted by Flippinstk View Post
    Timmy Jimmy,

    US NAVY Firecontrol solution answer..... (laymans terms)

    - A fired projectile will drop at the same rate and impact the ground as a non-fired projectile as long as the fired projectile does NOT have any elevation correction or hit anything in its path.

    -No matter what the caliber, size or powder charge, gravity acts the same on all projectiles.

    -Hold a firearm perfectly horizontal.
    Hold the same size projectile even with the end of that barrel at the same height.
    The instant the fied projectile clears the barrel the held projectile is dropped.
    Both projectiles WILL hit the ground at the same time.

    Inject a zero gravity, zero atmospheric condition or a elevation adjustment and the outcome will change.

    Its a simple process actually.... gravity works!
    This would be true if the barell remained motionless during fireing. Most bullets actually rise a bit initially after being fired because the barell has already begun to rise before the round has cleared the muzzle.

    This is why lighter bullets in a given caliber fired at close distance often impact lower than heavier bullets. They travel faster and clear the muzzle faster thus being less affected by the rise of the barrel.
    "The very atmosphere of firearms anywhere and everywhere restrains evil interference - they deserve a place of honor with all that's good.
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    Member Array Flippinstk's Avatar
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    Craze.

    My explaination was based on large bored ballistics. ie 3", 5", 16" guns. So with their rigidity there would be no barrel/muzzle rise while firing. Basic ballistics 101 explain every principle in a perfect world with a motionless barrel. I was simply trying to explain to Timmy Jimmy the basic principle of bullet drop and used the 2 bullets of the same caliber & weight explaination. I thought it was pretty simple and to the point.
    Alex G.
    S&W M&P .45
    Virginia Beach, Va.
    Senior Chief Petty Officer, RETIRED, USN
    Certified NRA Pistol Instructor
    NRA Range Officer

  7. #6
    Member Array Flippinstk's Avatar
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    But the same principles a applicable no matter what the caliber.
    Alex G.
    S&W M&P .45
    Virginia Beach, Va.
    Senior Chief Petty Officer, RETIRED, USN
    Certified NRA Pistol Instructor
    NRA Range Officer

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    Member Array Randy's Avatar
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    This is why lighter bullets in a given caliber fired at close distance often impact lower than heavier bullets. They travel faster and clear the muzzle faster thus being less affected by the rise of the barrel.
    Right you are - and not many people are aware of this effect. As an example, you can lay a 'medium barrel length' revolver upside down on its sights and note the barrel is pointing up in relation to the flat plane the sights are resting upon. This, of course, means the barrel is pointed down (and well below the sight line) prior to firing.

    This effect is typically only seen in guns (large bore handguns) where the support point is well below the axis of the bore. In other words, during recoil, a 'lever' is created (the support point is the fulcrum) and the muzzle must "flip" upward (and not straight back) prior to the bullet leaving the barrel.

    Randy

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    Senior Member Array cagueits's Avatar
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    Just somehting I found in the internet:

    http://www.chuckhawks.com/bullet_trajectory.htm

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    "bullet drop" is known as trajectory

    Using various ballistic calculators, one plugs in the values and the computer calculates the unknowns. Shooting Long range rifle, I have used them extensively at they are quite accurate as long as one knows the exact speed of the bullet expressed in FPS (feet per seconds). The only way to determine this is with a chronograph.

    A good ballistic program can be downloaded from the net that does a great job and is free. It can be found here...

    http://www.eskimo.com/~jbm/calculations/calculations.html

    Using the basic calculator, it shows to be:

    -21 inches at 100 yards
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    Member Array Randy's Avatar
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    I didn't think to post it before, but on the topic of ballistic calculators....

    I wrote one for use with the PalmOS. Nothing like being able to generate the data in the field when shooting. (long-range varmint plinking)

    It is on my web site and free for download. Once the site loads up (link in my sig line) click on "Miscellaneous" in the left frame then select PBX from the main section. Help yourself.

    Randy

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    Senior Member Array blueyedevil's Avatar
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    Well alot of the stuff is mostly right on this thread. Gravity is constant, though drag is not. Drag depends largely on the Ballistic coefficient of the projectile in flight (most handgun bullets are pretty low), and the density of the fluid it's moving through (air=barometric pressure/altitude). The other large component to "how flat it shoots" is initial velocity, assuming both drag and gravity are relatively constant, the faster the projectile begins flight at, the further the distance it travels before dropping a specified amount, which equates to a flatter trajectory curve.

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    Senior Member Array Timmy Jimmy's Avatar
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    Thanks guys this is exactly what I was looking for, and I was obviously not searching on the the right stuff in Google because I could not find the info.
    Timmy Jimmy

    If it is not in the US Constitution then the Federal Government should not be doing it.

    "Carrying a gun is a social responsibility."

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    Quote Originally Posted by Timmy Jimmy View Post
    How far out will a .45 ACP bullet in 230 gr stay flat and at what range will it start to drop and then how fast will it drop?

    If these are the wrong technical terms to use please educate me!
    I wounder if this is what your really asking, at 10-15 yds shoot at it; at 50 yds shoot over it. How much over it will depend on you, your handgun, and how the sights are set. You will have to experiment
    with each and every loading.

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