BIG Freakin’ Cartridge Test 011: RUAG SS109 (M855 Equivalent) 5.56mm NATO, 14.5″ Barrel, and Accuracy

    Next up for the Big Freakin’ Cartridge Test is RUAG Ammotec’s version of the NATO-standard SS109 round (equivalent to US M855). I believe the ammunition I tested may have been made in RUAG’s facility in Thun, Switzerland, although I have not confirmed that. The test procedure was as follows:

    1. Condition ammunition to 70 °F +/- 5 degrees for at least 1 hr (in practice ammunition was always conditioned overnight).
    2. Mount chronograph to barrel or rail.
    3. Record the temperature in the conditioned container before each string.
    4. Withdraw one round of ammunition from the cooler.
    5. Load and immediately fire the round.
    6. Cool chamber back to ambient conditions for 30 seconds
    7. Repeat steps 3 through 6 nine more times.

    This procedure was followed for 14.5″, 16.1″, and 20″ barrel length velocity tests. To measure velocity, a Magnetospeed V3 chronograph was used attached to the barrels of the 16.1″ and 20″ uppers, and the rail of the 14.5″ upper. In addition, three 10 shot groups were shot for each round through my Criterion 14.5″ chrome-lined 1:8 twist hybrid contour midlength barrel in .223 Wylde, to determine accuracy. These targets were then analyzed using OnTarget analysis software.

    The chronograph results for the 14.5″ barrel are as follows (Shot #, followed by muzzle velocity in ft/s):

    1. 2,857

    2. 2,879

    3. 2,904

    4. 2,944

    5. 2,906

    6. 2,913

    7. 2,918

    8. 2,923

    9. 2,923

    10. 2,929


    Which gave us the following figures:

    Min: 2,857

    Max: 2,944

    Avg: 2,909

    Standard Deviation: 25.2

    Extreme Spread (highest minus lowest): 87


    Being RUAG ammunition, I expected very good accuracy. What I got was, well…

    What on earth.

    It was around about the time I looked at the RUAG targets that I began to appreciate the value of shooting 3 10-shot groups, instead of just one. Any one of these groups would give someone a significant amount of pause – they certainly did for me. I had many doubts about these results. Surely I must have gooned up, been lazy in my marksmanship, or had some other unrecognized problem. Yet, with three groups, all consistently…well, inconsistent, it’s difficult to convince myself of any of those things.

    For the record, the results were an average (of all 3 groups) extreme spread of 8.434 MOA, with an average mean radius of 2.371 MOA. This is by far the worst result we have found so far in a BFCT evaluation. Compared to the lackluster results we got with the Golden Tiger, the RUAG is 71% bigger in extreme spread, and 54% bigger in mean radius.

    Oddly, even with these abysmal accuracy results, the consistency of the velocity for the RUAG wasn’t so bad, suggesting that there is some inconsistency elsewhere in the ammunition (such as the bullet). In addition, the average muzzle velocity was very close to what we’d expect for SS109/M855 from this barrel length, at 2,909 ft/s.

    16.1″ and 20″ velocity results will follow tomorrow.

    EDIT: RUAG International Sales Director Bert Roethlisberger reached out to TFB to help us understand the history of Lot T-17-001, and how it could produce such lackluster results. Bert’s comments are below:

    Bert here from RUAG Ammotec in Switzerland. I have read your test report with interest for the 5.56mm SS109 which was produced by us, RUAG Ammotec in Switzerland and would like to comment as follows.

    • As a norm we produce the 5.56mm SS109 NATO cartridge only for Military customers and never for civilian/commercial use.
    • The cartridges you were testing came from Lot # T-17-001 which was produced early last year for one of our military customer. As is SOP we continuously check the ammo for pressure, velocity and accuracy during the manufacturing process. About once every hour 50 rounds are pulled from the line and send to the test lab. During one of those tests variations in the loads was discovered and also the accuracy, by some samples taken, showed upper limit deviations and some even fell just out of specs.  Affected was also the velocity in some which showed greater than usual variations.
    • Based on those production test results our Q-team decided to stamp this Lot as “failed”, not for sale to the customer and it was pulled out.
    • We put approx. 550’000 rounds (Lot # T-17-001) in our warehouse and later on offered it to several commercial dealers as a one off special fire sale for anybody who wanted a good deal on 5.56mm ammo for backyard plinking.  This was made clear to the US dealer who finally purchased this Lot at a very good price.
    • This SS109 ammo was NEVER meant to be used for any accuracy testing but exclusively for plinking.  I like to stress again that it was ammo which failed our stringent quality requirements and therefore was NOT delivered to our Military customer.
    • RUAG Ammotec prides itself as being the manufacturer of high quality premium ammunition and we would never deliver inferior quality ammo to any customer unless as it is the case here it is made clear for what purpose this ammo should be used.”

    Reject lots are just a fact of life for ammunition production, and this ammunition is often released onto the commercial market as surplus. It’s certainly interesting to see how far “factory seconds” can deviate from what we expect of the real deal, though!

    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]