Note: I want to take a moment and thank Andrew Betts for this article. I often have tried to explain this to people and I don’t think they believed me. If you choose or have to wear body armor, be aware of its limits. And as always, try not to get shot. -Howard
Can a Tiny 45 gr .223 Varmint Bullet Defeat Level III Steel Armor?
By Andrew Betts
Level III AR500 armor is rated to stop 7.62x51mm NATO. It seems obvious that anything “less” than that would also be stopped. Is it possible that such a tiny bullet from a much less powerful cartridge could perforate armor designed and rated to stop the mighty 7.62x51mm?
As it turns out, yes. That tiny bullet can zip right through the steel armor, even when fired from relatively short barrels. How is this possible? It seems counterintuitive. It seems that it would require more power to get through steel armor but in fact, velocity is the primary factor that influences steel armor penetration. Sectional density, bullet construction, and mass all play a role, of course, but the roles they play are minimal compared to the role played by velocity. In the case of ¼” thick AR500 steel, 3,200 fps is about the cutoff point. Anything faster than that will usually pass through and anything slower will probably be stopped. The actual V50 rating is not published by the company, but it is apparent that it is somewhere in the neighborhood of 3,200 fps. The V50 rating is the velocity at which 50% of the projectiles of a given type pass through. To determine the V50 rating, a laboratory increases the velocity of the bullet being tested until it perforates the armor, then tests statistically relevant sample sizes at velocities near that point to determine the velocity at which 50% of bullets pass through.
It may be tempting to declare that this armor is garbage, but that is far from the case. This test simply demonstrates the design limitations of this type of armor. The plate shown in this test is available for $65 from http://www.ar500armor.com and will stop all handgun rounds and most common rifle rounds such as 7.62x39mm, 7.62x51mm, .300 Blackout, and even most .223 or 5.56x45mm ammo. While it is not specifically rated for M855, this plate will stop multiple hits of it. It will not stop M193, if it is fired from a long enough barrel and impacts at a close enough distance, but it will stop virtually any 60 grain and heavier .223 Rem projectile. Moreover, it will do so even after significant abuse. As we saw in the video, the plate stopped two rounds of 7.62x51mm, even after it had been perforated multiple times by the varmint ammo. Rather than focusing on the few threats that it will not stop, consider that you cannot purchase any lower threat level for the same cost. It stops far more than Level IIIA soft armor does and costs much less.
It is also worth noting that, while the high velocity varmint ammo does a good job of getting through the steel plate, it is not a good choice for defense. As seen in the test below, it penetrates far too shallowly to achieve reliable incapacitation.
Finally, it bears mentioning that the same company that produces this armor also produces Level III+ steel armor, which is designed to stop many of the threats that can defeat Level III armor. Be wary, though. Level III+ is not an actual NIJ rating, just an affirmation by the maker that the plate exceeds Level III by some degree in their assessment. Some manufacturers have had independent labs test their Level III+ plates and give them a special threat rating for specific rounds and others have not. Just because the plate is advertised as a Level III+ does not mean the same thing for various manufacturers. As with any other purchase you must do your own research. You should do your level best to find independent testing results from qualified labs and where that is not available, amateur testing as seen in the video above can help to inform your decision. As always, software > hardware. What is between your ears matters far more than what is on your chest. Train hard.