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┬áreleased 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┬átesting 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. He can be reached via email at [email protected]