Does Pointing Your Gun Up Affect Accuracy? ARDEC Study Reveals the Effect of Weapon Orientation on Ammunition Velocity and Consistency [NDIA 2017]

Does pointing your gun up or down affect its accuracy? The answer is “maybe” according to a recent US Army Armament Development, Research and Engineering Center (ARDEC) presentation released at the 2017 National Defense Industry Association small arms conference. The presentation covers a study conducted by ARDEC which examined the effect of ullage (free space in a loaded round) and orientation on the consistency and velocity of small arms ammunition.

A slide from the ARDEC presentation showing x-ray images of .50 caliber ammunition in different orientations. The red arrows point to the free space in the round; note how the position of the free space changes depending on the round’s orientation.

 

The findings of the study may not be exceptionally surprising – it turns out that rounds with more ullage are less consistent – but they are remarkable in how detailed they are. The ARDEC team testing followed standard EPVAT procedure, accounting for pressure, velocity, and and action time (the time between ignition of the primer and the bullet leaving the barrel):

A slide from the ARDEC presentation, showing the test data for 5.56mm M855 ball and M856 tracer ammunition. Note the low difference between results at different orientations; this is due to the fact that both M855 and M856 have very low ullage.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Martin Grønsdal

    it is up to the tactical operator to operate in such a way to benefit from the free space and use that to his/her advantage.

    • some other joe

      Advice for tactical operators operating tactically on tactical operations seeking operationally tactical advantages. Of course.

  • ExMachina1

    I would predict that pointing a gun up vs down will affect where the bullet goes by about 180 degrees

    • USMC03Vet

      what in tarnation?!

      • jcitizen

        I think it is west of Timbuktu.

    • Gary Kirk

      Ahhh.. But if one fires up on the east side of the earth.. Is he not firing down on the west side??

      • supergun

        Well,,,,that is a deep subject. Don’t you have to point it up to hit something far away? That would definitely affect accuracy either way.

    • supergun

      Right answer.

  • Rnasser Rnasser

    Thanks Nathaniel!

    Do you have a link to the complete small arms NDIA 2017 prosentations?

  • adverse4

    I suppose everybody has to have something to do.

  • R. Kenneth Thorstenson IV

    Thus for accuracy testing, one should always fire 1 round to settle the action and ammunition before firing a 3 or 5 round group.

    Interesting.

  • Edeco

    I have a theory that pointing the gun up affects the trajectory.

    • supergun

      You may have hit on something there.

  • Keiichi

    So, then, the most consistent ammo would have the bullet seated on the propellant?

    • John Cheek

      “OVER PRESSURED”

  • uisconfruzed

    Handload & use a powder that fills the brass.

  • bthomas

    Re: OP. Old business. Common knowledge to anyone who has ever spent time on a firing line. Orientation of powder at time of firing affects POI. Proven in testing at US govt. armories in past eras using various cartridges, firearms, etc.

  • rc_vic_kerman

    If the powder lights off better while it is hitting or sitting on the primer then why not place some kind of medium on top of the power load and then seat the lead so as to keep the power stable at any angle?

    • jcitizen

      Back when pressures were low, I seem to remember reading old data that cotton was used. But now you wouldn’t dare – probably because it could cause a pressure spike with the bottle neck. I should think a very little patch of rice paper soaked, then dried in potassium chlorate or flash paper would work. You can buy it a Walmart, but it is pretty expensive.

    • Gordon Couger

      Cream of Wheat, Kapok, over powder wads, over powder wads with Cream of Wheat ,Kapok or Dacron fluff. Still do it on light carges,

  • Frank K

    Hey..Many of us experience our ups and downs it’s part of life.

  • survivor50

    Try a 44 Mag with a downloaded charge…point down before aiming level at the target. All the powder moves away from the primer, and on firing with a level barrel, you get a wonderful pop, and then a FIREBALL of powder exiting the barrel then igniting !!! Not accurate at all, but very entertaining!!!
    Ain’t reloading fun…

  • John Cheek

    This is dumb. “POINTING” the gun is a bad term. Pointing it at the target is most effective.
    Now, “CARRYING” it with the barrel up or down is more to the point of the subject of the article. While “CARRYING” the gun with the barrel slanted down, ie, with the ammo nose down will in effect allow the powder to move to the bullet end of the case and therefore, place it against the bullet, allowing the empty space to be at the rear near the primer, thus causing more effective pressure and velocity.
    WHO WRITES THIS TRASH?

  • I hope you’re kidding

    • georgesteele

      Jeez, I hope you’re kidding – did the “breech flash is a beatch” not give it away? Muzzle flash is pretty low when nothing comes out . . .