Will Level III Armor Stop High Velocity 5.45mm?

By Andrew Betts

7N6 is some of the warmest 5.45x39mm ammunition available in the US, and it has a steel jacket. What’s more, 53 gr 7N6 is narrower and therefore has a higher sectional density than 5.56x45mm 55 gr M193, which we have already seen can easily defeat level III AR500 armor. Level III is not rated to stop 5.45x39mm, either so this was a difficult one to call.

At first glance, these results seem to be pretty definitive. The plate did stop the round. End of story, right? Maybe not. The impact velocity was 3,167 fps, which was just below the 3,248 fps that compromised an uncoated plate in an earlier test of .223 45 gr varmint ammo. That velocity difference is close enough that one shot cannot really be conclusive. Without at least a five shot average to determine extreme spread for the velocity of that load, we cannot know if the round that hit the plate was at the high or low end of the normal velocity range. Commie ammo has been known to have somewhat inconsistent velocity at times.

While the coating on the plate is not intended to provide any extra ballistic protection, with the velocity so close to the failure point of this plate, it is possible that the coating slowed and/or yawed the bullet just enough. It is also possible that the impact occurred right at or near the V50 of the plate for that round. That is the point at which 50% of the rounds will make it through and 50% will be stopped. It could simply be that this test represents a “lucky” shot.

We hadn’t noticed how close that velocity was to the previous failure point until we got home or we would have fired more rounds at the time. Rest assured, we will repeat the test when we have the opportunity. In the interim, it is interesting to know that this type of armor at least has the potential to protect against threats which substantially exceed its rating.