Variations Between Common 5.56 and .223 Remington 55 Grain Loads

    As I am sure many would attest, being “Mil Spec” does not necessarily mean that something will be the exact same between different manufacturers. Manufacturing methodologies, tolerance stack-ups, etc all contribute to variations of the same product. A prime example of this is various military weapons from World War 2 and today.

    In a remarkable comparison, shooter Jonathan Ocab cataloged differences between various common 55 grain .223 and 5.56 loadings, some of which purport or are reported to be “Mil-Spec.” As part of the comparison, Jonathan looks at the pulled bullets, powder composition, accuracy, velocity standard deviations, etc.


    While the testing methodology still has some holes in it (all were using the same barrel, which various loads are known to like some barrels over others and he discounts “flyers” which are often actually part of the base accuracy), the conclusions and results are still real-world applicable.

    The ammunition tested includes:

    • Federal “American Eagle” AE223 55gr .223 Remington
    • Federal “American Eagle” XM193 55gr 5.56 NATO
    • IMI M193 55gr 5.56 NATO
    • Independence XM193 55gr 5.56 NATO
    • PMC X-TAC XP193 55gr 5.56 NATO
    • Winchester Q3131 55gr 5.56 NATO
    • Wolf Gold .223 Remington

    Check out Jonathan’s article on his website here. The results are interesting including the solid performacne of ammunition that is not as highly “rated” by the internet community.

    Nathan S

    One of TFB’s resident Jarheads, Nathan now works within the firearms industry. A consecutive Marine rifle and pistol expert, he enjoys local 3-gun, NFA, gunsmithing, MSR’s, & high-speed gear. Nathan has traveled to over 30 countries working with US DoD & foreign MoDs.

    The above post is my opinion and does not reflect the views of any company or organization.