How far does it go?

Discussion in 'Caliber Corner' started by Shiloh228, Feb 20, 2013.


  1. I know there's a lot of information here on GT...ammo data tables, etc...but I couldn't find what I'm looking for using the "search" tool...so please direct me to the right thread(s).

    I was asked by a non-shooter "how far does the bullet go...at what distance will it not hurt someone?" (i.e., pierce the skin). She was concerned about safety of outdoor shooting (probably inspired by Joe Biden's recent suggestions...)

    I know...I could dust off my dynamics textbook, calculate distance when velocity=0 given a specific muzzle velocity, drop distance due to gravity, etc, but...I know there must be data (published by the manufacturers?)...and I suspect it's here on GT.

    So...hypothetical:

    • 9mm 115gr FMJ
    • fired at height of 5 feet off the ground
    • axis of gun parallel to ground
    • no obstructions, ground absolutely level
    Questions:

    1. how far will the bullet travel before it hits the ground?
    2. what is minimum velocity for bodily injury? (i.e., pierce bare skin)
    3. what is distance for (2)?
    Bonus question:

    • if you fire same round straight up in the air, what is the velocity of the bullet when it comes down and strikes the ground? (hopefully not someone's head)
    Thanks for the help!
     

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  3. Well people have been killed by bullets fired a mile a way. Bad luck is bad luck. At 5 feet above the ground, a 9mm @ 1200fps is hitting the dirt before it gets 250yds. Elevate the muzzle at all, even a slight amount, & the bullet is going to travel a lot further. Shot @ about 45deg angle, it will travel almost a mile.
     

  4. On the other end (for example) the M2 (50 cal machine gun) has a max range of 4.2 miles. A few yours ago in the DFW area a lady was killed walking to her car after church let out by a 50 cal bullet to the head. From the angle of the impact and direction, it was thought the round was fired from a field four mile away. The shooter was never identified.
     
  5. #4 M 7, Feb 21, 2013
    Last edited: Mar 19, 2013
  6. OMG! Just amazing...definite fave...thanks!
    :bowdown:
    Maybe I will have to dust off the Dyanamics text...

    Sort of a variation on:

    • give a man a fish, he will eat for a day
    • teach him to fish, he will eat for a lifetime
    and...

    • give him 10,000 fishing rods, the boat will sink
    Seriously...thanks! I will definitely spend some time working on this.:supergrin:
     
  7. Happy to help.

    If you like this sorta stuff check out the "Energy Column" option- you will also see that it has an output for the Krupp Tank Penetration formula. The "geek" potential is high on that 'site, but for shooters who like exterior ballistics and bullet penetration models, it is the best place there is. :supergrin:
     
    #7 M 7, Feb 21, 2013
    Last edited: Feb 21, 2013
  8. Know your backstop. Best case scenario is to shoot at targets lower than bore height with a good backstop (dirt mound) as tall as possible. I was shooting at plates yesterday from 75-100 yards. 165 gr. 40's @ 1150 muzzle took about 1 second to hit. The 165 gr. 10mm @ 1400 took about 3/4 second. I had'nt shot plates at that distance in a while and was surprised how much the bullets slowed down in that distance.

    As was mentioned above, angle of the barrel has most to do with how far any given bullet will travel.
     
  9. YOU SIR, are in dire need of a copy of HATCHER'S NOTEBOOK where all such things you ask thereof are covered. IF it is not in there you have no need of knowing it.
     
  10. SCmasterblaster

    Millennium Member

    Another bookmarked site - thanks!
     
  11. I do not know about magnum rounds and the 10mm, but we were told the 9mm and 40 S&W can be lethal for over a mile. As Fred mentioned, the gun would have to be shot from an upward angle. I do not have the caculations for this.
     
  12. "So...hypothetical:

    • 9mm 115gr FMJ
    • fired at height of 5 feet off the ground
    • axis of gun parallel to ground
    • no obstructions, ground absolutely level
    Questions:

    1. how far will the bullet travel before it hits the ground?
    2. what is minimum velocity for bodily injury? (i.e., pierce bare skin)
    3. what is distance for (2)? "
    Here's something i heard before. If you fire a rd say parallel 5' off the ground and drop a projectile (bullet) same weight from muzzle end (same height) same time both projectiles will hit the ground at the same time? Some kind of rule of gravity or what not. Not sure i can grasp this logic though. Anyone know?
     
    #12 glock031, Feb 22, 2013
    Last edited: Feb 22, 2013
  13. +1 We have a winner.

    For the questions posed;

    If the gun barrel is parallel to the ground then the projectile will impact a relatively short distance from the muzzle. It will impact the ground the same moment an identical projectile, dropped at the same instant from the muzzle as when the shot is fired, will hit the ground. (yeah, I know there are variables such as wind resistance, but for the purposes of this discussion that answer will do nicely)

    If you fire a projectile at a 90 degree angle to the earth, the projectile will reach zero velocity at some point and come back to the earth at a terminal velocity determined by a number of variables; does the projectile turn to point the nose (narrowest part) toward the earth or does it come down base (flat part) first? What is its sectional density and ballistic coefficient? Gravity will be pulling the object toward the earth and the air will retard its speed.

    From memory, a .30 caliber military round will have a terminal velocity of around 350 fps.

    As was stated, this is all in Hatcher's Notebook, which is not in front of me at the moment.
     
    #13 ChiefWPD, Feb 23, 2013
    Last edited: Feb 23, 2013
  14. Excluding the effects of wind resistance, that is true. Gravity causes both bullets to fall at the same rate 32' per sec. per sec. The parallel velocity of the bullet has no effect on the action of gravity.
     
  15. SCmasterblaster

    Millennium Member

    32.159 FPS per sec, actually.
     
  16. I thought I heard it hit the ground a little sooner... :cool:
     
  17. RoyHinkley

    RoyHinkley Bonafide User

    139
    0
    86
    So it would be pretty easy to determine the distance it would travel at a constant velocity, but how do you determine the deceleration rate of the projectile?


    Posted using Outdoor Hub Campfire
     
  18. SCSU74

    SCSU74 St. Cloud Proud

    You sure that wasn't at TMS? A .50 cal round fired at a nearby range deflected off the berm and came down through a ladies camper.


    Posted using Outdoor Hub Campfire
     
  19. SCmasterblaster

    Millennium Member

    HehHehHehHehHeh!!!
     
  20. There are charts of a projectile's ballistic coefficient, their ability to penetrate air. Don't know how they figure the numbers.

    :dunno:
     

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