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Hard Armor 101, General Information, Material Differences and Common Misconceptions

Updated: Mar 21

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We get it, body armor is a complicated subject. There’s many kinds of materials, with their own distinct advantages, disadvantages and properties. Then there’s different ratings, shapes, cuts and curves. To add to that, it doesn’t help that some manufacturers don’t disclose all the information you should know as the end user.

In this article, I am going to shed light on the properties (as well as pros and cons) of Ceramic and Steel plates. I will cover some basic armor testing parameters and explain what the NIJ is. I also hope to clear up some common misconceptions about these types of armor, and provide general information so you can make an educated choice when choosing what armor to trust your life to. This is not blanket information for everything nor does it cover everything, not all armor is created equal, even those in the same category. This is just a basic guide for those who are curious and should give a baseline set of knowledge on the topic. There will be exceptions and I will speak about a few of them.

For our purposes, we will only be discussing rifle threat rated body armor, specifically NIJ 0101.06 Level III and Level IV. (NIJ 0101.06 is the most up to date NIJ rating system, there are others such as 0101.04 or 0108.01, but those are previous older revisions). This article will demonstrate the basic necessities of the important topics when dealing with understanding body armor.

What is the National Institute of Justice (NIJ)? What is an NIJ certification?

The NIJ establishes minimum performance standards for body armor and conducts testing against these standards to ensure that body armor complies with the standards. In other words the NIJ establishes a BASELINE MINIMUM for the performance of armor.

If a specific piece of armor has passed the rigorous NIJ certification process, it means said armor has consistently proven to stop the prescribed ballistic threats in a lab environment, as well as simulated adverse conditions and damage. Additionally, it also means there is a degree of quality control assurance (in the form of the NIJ FIT) which is a regular random quality control inspection.

What goes into an NIJ certification? What are the tests?

9 Plates are provided by the manufacturer for an NIJ Level 3 test, to each be shot 6 times. 37 plates are provided by the manufacturer for an NIJ Level 4 test, to each be shot once. These armor plates are split into two groups. One to be shot without any tempering or torture testing, and the others to be shot with tempering and torture testing.

The following are the main tests that plates are subjected to. (I will go more in depth in a different article)

1) Drop Test:

Armor undergoes a drop test, where a 10lb weight is strapped to the back of the plate, and it is dropped onto a hard-concrete surface at a 90-degree angle from no less than 4 feet. This is done twice. The armor is not dropped on its edge, but on the strike face. (Then the plates are subjected to the shoot test)

2) Heat/ Cold Chamber:

Plates are placed in chambers that are kept at 5 degrees Fahrenheit, and 149 degrees Fahrenheit respectively. Additionally, during the thermal cycling phase, a plate is placed in a chamber that cycles inbetween 5 degrees Fahrenheit and 194 degrees Fahrenheit for 24 hours. (Then the plates are subjected to the shoot test)

3) Water Submersion:

Plates are submerged completely in water and shot while dripping wet.

4) Shooting tests:

Plates are strapped to ballistic clay (to aid in measuring back face deformation), and shot. Cartridges are hand loaded to ensure consistency and velocity is measured. Backface deformation is then measured (it must be under 44mm).

The National Institute of Justice (NIJ) lists the following threats as their minimum standard for Levels III and IV respectively. 1) For armor to be rated NIJ Level 3, it must stop 6 rounds of 7.62x51mm NATO Ball (147gr) fired from 15m at a velocity of 2780 (+/-30) FPS. 2) For armor to be rated NIJ Level IV, it must stop 1 round of .30-06 M2-AP (166gr) fired from 15m at a velocity of 2880 (+/-30) FPS. REMEMBER, to officially earn the rating they are required to ONLY test against that caliber of ammunition at that weight and velocity. Again, a minimum. But it does not mean it will only stop said threats. For example, a level 4 plate will confidently stop M855A1, as it is a lesser threat.


This is an important term or test to know. A test for ANY round outside of the NIJ prescribed minimum (7.62x51mm M80 Ball for Level III and .30-06 M2-AP for Level IV) is considered a "Special threat". Manufacturers can request their own parameters for Special Threat tests, so make sure to read any provided testing reports to ensure they have them tested to the NIJ standards.

**Special Threat Plates**

Special threat plates represent a gap in NIJ ratings. It is neither Level III nor Level IV, it is below Level III and Level IV. Often special threat plates are only capable of stopping 5.56x45mm M193, M855, 7.62x39mm MSC or FMJ. Sometimes special threat plates can stop a single shot of 7.62x51mm M80 ball, but cannot stop the 6 shots required for level III. It is incredibly important to look at product descriptions to see what specific rounds a special threat plate can stop, and to not go off of assumptions or rumors. For example, the Hesco L210 cannot stop .308 M80 ball period, the RMA 1003 SRT can stop a single shot of .308 M80 ball, but not the full 6 rounds required for Level 3 certification.

US Military issued Ceramic plates are not NIJ certified, they are tested to Mil Spec standards. The NIJ is a civilian ballistics testing standard generally meant for domestic LE. I am going to include some rough ratings as the information is not available to the general public. SAPI/ ESAPI plates are a very specific military plate, tested to military standards. Not all “SAPI cut” plates are actual SAPI plates (if that makes sense). 1) SAPI: Must survive 3 hits total in conjunction with an interceptor vest containing soft armor backing from, M16 (5.56x45mm/ .223 M855/ SS-109) Green Tip, Dragunov (7.62x54mm R-LPS) Russian Light Penetrating Steel and FN FAL (7.62x51mm) M80 ball. The later "ISAPIs" which preceded ESAPIs were additionally rated for 3 shots of 7.62x39mm BZ API.

2) ESAPI: ESAPI Rev A-E: 3 shots of 7.62x51mm M80 ball, 3 shots of 7.62x54R LPS, 3 shots of 5.56x45mm M855, 2 shots of .30-06 M2 AP ESAPI Rev G: 3 shots of 7.62x51mm M80 ball, 3 shots of 7.62x54R LPS, 3 shots of 5.56x45mm M855, 3 shots of .30-06 M2 AP, 3 shots of 7.62x54R 7N1, 3 shots of 5.56x45mm M995. ESAPI Rev J: 3 shots of 7.62x54R LPS, 3 shots of .30-06 M2 AP, 3 shots of 7.62x54R 7N1, 3 shots of 5.56x45mm M995.

Some terms to know:

  1. In Conjunction With (ICW): This means this armor (generally Ceramic or Polyethylene) must be worn in conjunction with soft armor (generally 3A) to reach its maximum efficiency.

  2. Standalone: This means this plate will stop its maximum rated threat alone and without need of soft armor backing (A backer is built in)

  3. Single Curve/ Multi-Curve: This is how many bends are in the armor plate itself. Single curve means the plate has a single curve, vertically along the middle. Multi-Curve means that there are multiple curves, most commonly the edges are curved in to contour better to your body. For extended wear, multi-curve is suggested as it is significantly more comfortable.

Different cuts of armor:

There are two primary common rifle armor plate cuts and that is the SAPI/ ESAPI cut and Swimmers/ "Swimmers Style" cuts.

SAPI/ ESAPI cut plates are your standard plate shape, military issued SAPI/ ESAPI plates come in this cut. The military standardized SAPI/ ESAPI sizing is 8.75x11.75 (S), 9.5x12.5 (M), 10.25x13.25 (L) and 11x14 (XL). There are also civilian sized plates that utilize the same style profile/ cut in 8x10 and 10x12.

Swimmers cut plates are traditionally based off of the military Socom SPEAR swimmers cut plates which were literally meant for swimming in. They feature a more generous shoulder cutout for increased range of motion and mobility, which also makes shouldering rifles easier. This more generous cutout also means marginally less material coverage around the shoulders, which can decrease weight by a slight margin.

Then, there is a third type of cut, the "Shooters cut". This is a term that is used without consistency within the armor industry. Depending on which manufacturer you ask, "Shooters Cut" could mean 10 different things, ranging from 10x12 SAPIs, Swimmers cuts, proprietary cuts and more. However, the original shooters cut (before it was adopted inconsistently as a term) is shown below (in the middle). Generally these come in 10x12 and feature the same top profile as SAPI cut plates, but with additional smaller angled cutouts at the bottom. All of our shooters cut plates are in this shape. We generally categorize our Shooters cut plates with our SAPI plates as the profile is the same, this is to avoid confusion and fitment issues.

Proper sizing and fitment of armor plates: (Remember, you buy a vest to fit your plates, not the other way around) General rule of thumb is the edges should line up with your nipples or cover them slightly. Wear your front plate so the top of the plate is two finger widths below where your sternum ends. Then the bottom of the plate should end about 1-3 inches above your belly button WHEN YOU ARE SITTING DOWN.

What I have generally seen is your plate size is 1 size below your shirt size (for men). Remember, the armor plate is meant to cover your vitals, not your entire torso.

For 85% of individuals a 10x12 or Medium SAPI (9.5x12.5) will work to cover their vitals. Even for overweight individuals its important to remember that your internal organs and ribcage do not expand as you put on weight. So while you may want a larger plate such as a Large or an XL, often times a 10x12 will provide you with sufficient protection for your vitals. Although for larger individuals I do generally recommend a large, as that provides more coverage, but does not come with as much of a weight or mobility penalty as XL plates bring.