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

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Table of Contents (Click on the links to skip to sections)

1. NIJ Standards, Certification, Tests and Levels

2. Different Cuts and Shapes of Plates

3. Sizing and Fit of Armor Plates

4. Common Misconceptions

5. Different Types of Armor Materials Comparison

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.

The National Institute of Justice (NIJ) Standards and Certification

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.

**SPECIAL THREAT TESTING**

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 Tencate CR6450SA can stop 1-3 shots 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.

The Different Cuts/ Shapes of Hard Armor Plates

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.

Common Misconceptions

Now that we’ve gotten past the scientific part, let’s talk about some of the common misconceptions/ topics of misunderstanding when it comes to body armor.

1. Level III+ or other "plus" rated plates

The "+" label that manufacturers use on plates is generally to denote that said plate has been tested against special threats outside of what the NIJ uses which is 7.62x51mm M80 ball for Level 3 and 7.62x63mm M2 AP for Level 4. While the actual "+" itself is not an official NIJ designation, this does not mean the entire plate is using a made up rating system. For example, Level III+ means the plate stops the base NIJ .06 level 3 threat of 6 shots of .308 M80 ball, PLUS whatever additional special threats the manufacturer has tested against it. This additional threat can be anything, from 5.56 M193 or M855, to M855A1, 7.62x54R B32 API, etc. Not all level 3+ plates are made equal, it is important to look at what additional threats the manufacturer has tested the plate against.

2. Ceramic is not as fragile as everyone makes it out to be.

It seems that many people are under the impression that Ceramic armor is like glass and needs to be babied otherwise it’s going to shatter and lose all its ballistic capabilities. I have mentioned before that Ceramic plates must undergo a drop test during their certification process. 2 drops, from 4 feet onto hard concrete with 10 pounds strapped to the rear. This is a far harsher drop than you will likely run into during regular use. Now… this does not mean you should go throwing your Ceramic plates across the room or using it as a hammer. You should not drop your Ceramic plates, but if it is dropped once on its strike face from table height, you’re likely ok. The 23rd International Symposium on Ballistics performed a scientific study on the effects of cracks on the performance of a ceramic plate. Titled "The Effect of Cracks on The Ballistic Performance of Contoured Protective Body Armour Plates" written in 2007 by Celia Watson, et. al. In this study they evaluated 6 batches of plates across 12 years of production dates, with the 6th batch being the oldest. The 6th batch had visible damage, micro fractures (cracks) and were considered to be discarded out of service plates. During testing they placed the plate under a hydraulic press and caused cracks in the center. They then X-rayed to confirm a crack and placed a single shot of 7.62x51mm M80 ball directly onto the crack. They found that all of the first 5 batches performed on average 15% above specifications, or at least 10% above specifications, even when severely cracked. The 6th batch, they found on average they still performed 12% above specification, despite being so old and visibly damaged.

The plates tested in this experiment were British CBA plates. It is rated for M80 ball in-conjunction with a fragmentation vest. These fragmentation vests had a rough rating of NIJ level 1 (meant for shrapnel). So the plates tested were most comparable to NIJ Level 3 standalone or NIJ Level 3 ICW plates.

3. The 5 year “expiration date” armor manufacturers put on armor is when the WARRANTY expires (Ceramic Armor Does Not Expire).

The expiration date on armor is the expiration of the warranty, a way to limit the liability of manufacturers, this is standard practice with most safety products. The expiration date is NOT when the armor becomes unserviceable. The ceramic itself does not degrade. The PE/ Aramid/ Fiberglass backing material does not ever degrade to an amount significant enough to cause penetrations. Adhesives in modern ceramics are like a heat and moisture resistant epoxy, it takes a lot more than you'd think to cause that to separate.

You can very simply verify serviceability at home by doing the tap and torque test. If it passes both, its good to go. If it passes only the torque test, its still good to go. If it fails both or fails the tap test, I would replace it, but these are generally incredibly worn or heavily used.

Tap and Torque test: (You can use a metal knife as the tap tool) https://www.youtube.com/watch?v=31dO_Xyj5ik

As mentioned in the previous portion, in "The effect of cracks on the ballistic performance of contoured protective body armour plates" (Celia Watson et. al), the oldest batch of test plates were 12 years old at the time, which would have made their production date 1995. This oldest batch was X-rayed to confirm internal micro fractures and the plates had visible external damage. However the damaged plates all still performed at least 12% above the required specifications against the .308 M80 ball test round. Please note, the internal micro fractures were not degradation from age or from storage.

Next piece show a video of a Vietnam era Ground Troops Variable Body Armor vest being shot. This is the earliest example of an issued ceramic armor plate, so there are no examples of ceramic armor being issued at any sort of scale before this. These plates were made in 1969, so at the time of the videos filming (2021), those plates are 52 years old.

These plates are rated for .30 cal ball, which is .30-06 M2 FMJ ball. These plates stopped all the threats it was rated for and it was only penetrated by a 7.62x54R Steel core round which it was not designed to stop.

Video: https://www.youtube.com/watch?v=1z7NJBqPVBM

Take care of your armor and it will take care of you. Don't throw it haphazardly off of the top of trucks or play frisbee with them and you will be fine. Use the tap and torque test if you are ever unsure.

4. “Ceramic is not Multi-hit” For a properly made Ceramic armor plate, this is completely false, any properly made ceramic armor plate will be able to withstand multiple strikes from ballistic projectiles. However, the amount of hits said plate can take depends entirely on the level of protection, construction and the round fired at it. As mentioned before, an NIJ Level 3 plate must stop six (6) rounds of 7.62x51mm M80 ball, this includes all Ceramic plates that are rated level 3. Level 4 plates however are only tested against a single shot of .30-06 M2 AP, this does not mean a level 4 plate is incapable of withstanding more shots, it simply means it is what the test is subjected to.

When a plate is shot, it damages the ceramic locally, other shots placed around the initial hole(s) will likely still be stopped. The ceramic core should be glued to a polymer ballistic backer, which prevents the monolithic ceramic tile from shifting after cracks propagate through the plate. As also mentioned in #2 cracks do not affect the ballistic performance of armor to a large degree. This is why all properly made standalone ceramic armor plates should have a strong adhesive bond between the ceramic material and backing material with means of a waterproof and heat resistant epoxy like adhesive. Simply put, when a round strikes the ceramic plate, the damage is localized because the ceramic is glued to the backing material. The ceramic material shatters locally, and other parts of the plate (often even just 1" away) can still stop rounds. Any quality or properly made Ceramic Level 3 or Level 4 plate will be multi hit capable against .308 M80 ball or rounds such as M193.

The construction of a Ceramic Level 3 and a Level 4 plate utilize the same principals. The ceramic strike face weakens, blunts and or shatters the projectile for the ballistic backing material to catch. Level 3 and Level 4 plates can use the same exact materials (for example, Spectra Polyethylene and Bitossi Alumina Ceramic), but the difference simply comes down to the amount of each material used and the ratios. Level 4 plates generally will use more ceramic material. With that being said, all Level 3 ceramic plates are multi hit due to NIJ testing requiring 6 hits, and all Level 4 plates are also multi hit due to the same design principals. A properly made quality ceramic level 4 plates will easily defeat multiple hits of lesser threats such as 6 shots of .308 M80 ball, 10 shots of M193, M855 or M855A1, etc. However, not all ceramic level 4 plates are capable of stopping 2 or more shots of .30-06 M2 AP (the Level 4 test round).

5. MIL-A 46100 steel armor is NOT rated to stop .30 cal (.30-06 M2-AP) at a 90 degree angle of strike. This type of steel was designed as vehicular armor, and was therefore tested with vehicular usage as its end use and not body armor. MIL-A 46100 steel armor is rated to stop .30 cal when the plate is at a 30 degree ANGLE. Angling armor increases its effective thickness.

6. Putting armor on the ground and shooting it in your back yard is not a valid means of testing the ballistic capabilities of said armor. I’ve linked the parameters for NIJ testing and a video. Unless they’re at a minimum backing the plate with clay and using a chronograph, it doesn’t mean much. (Unless it penetrates… if it penetrates then clay won’t matter) Back-face deformation is just as important as penetration/ non-penetration and can often tell you a lot about a plates reliability.

7. Ceramic plates do NOT spall.

Some of you may have seen AR500’s video with the balloons, where a ceramic plate supposedly “spalled” and popped a bunch of balloons. This is a perfect example a video that (in my opinion) is misleading. The “spalling” witnessed in the video are ceramic shards. Those shards are traveling at a relatively low velocity and are harmless. They can pop balloons because balloons present very little resistance. Sticking a Ceramic plate in a vest will ensure these shards do not even scratch you, as they cannot make it through the thick fabric of the plate carrier. The fragmentation from steel plates presents a far greater risk, it is traveling at a high enough velocity to penetrate your plate carrier fabric and still cause bodily harm.

8. Uncertified, Relabeled Chinese made plates are NOT "Just as good"

I often see people saying "Why spend more on Highcom, LTC or Tencate when I can get (X Chinese plate) for $99? Simple. They are always uncertified, and made overseas with no quality control assurances. As mentioned previously, all NIJ certified plates must undergo regular FIT testing. Plates are pulled at at random, shot and evaluated. Notices are put out when plates fail said tests. Chinese plates will often use ceramic material with a far lower purity than domestic counterparts and will often utilize lower grade and weaker backing material. A common theme I have also witnessed is incredibly weak adhesive bonding. When deconstructing a plate, I should not be able to separate the ceramic material from the backer easily with my hands. These all have great impacts on the performance and longevity of the armor and will greatly affect long term effectiveness. Weak adhesive bonding is the sign of an improperly made ceramic plate, these may function when they are new, but generally will begin to degrade and separate over time. So cheap Chinese plates purchased today will not have the same performance 3 years down the road, while properly made domestic counterparts will likely not experience degradation of capabilities for decades.

Time and time again I have witnessed ballistic "tests" on YouTube which show excessive amounts of backface deformation and clear catastrophic delamination of the backing material. Excessive backface deformation equates to more blunt force trauma and energy your internal organs are subjected to absorb.

It's important to also read the fine print for some of these armor plates. For example, LAPG plates are surrounded by an inch of non ballistic foam. Their 10x12 plates are in reality only offer 9x11" of ceramic coverage. No reason to purchase Chinese uncertified plates when US made and certified plates can be bought for $389 a set.

You can read more on our standalone article here: https://www.apexarmorsolutions.com/post/why-it-s-important-to-buy-quality-nij-certified-not-just-tested-armor

Different Types of Armor Material Comparison

Now that we’ve gotten past some of the common misconceptions, let’s look at some of some of the common materials making up rifle threat rated body armor and some pros/ cons and information on them. For simplicity sake, I’m not going to go too in depth as it can be rather confusing. This also isn’t a blanket guide, different manufacturers use different blends of materials and can in turn produce plates with very different threat ratings. I’m not going to talk too much about the different composites and blends as there’s too many.

1. Ceramics. “Ceramic Plates” are actually a fairly broad category. To simplify this, we will define Ceramic plates as any plates that utilize a form of Ceramic (Al203, SiC, B4C) as the strike face/ Core. With the exception of ICW plates, there generally are no “pure” Ceramic plates. Most plates on the market nowadays are standalone, which means they utilize a ballistic backer. This backer is generally made of Polyethylene, Fiberglass (or sometimes Kevlar). This backer is used to absorb blunt force trauma, as well as catch any bullet fragments or projectile jackets that penetrate through the core. The majority of civilian Ceramic plates are composed of an Aluminum Oxide Ceramic core/ strike face and a Polyethylene or Fiberglass backer. Some higher end lightweight solutions may utilize Silicon Carbide or Boron Carbide Ceramics to achieve a lighter weight. Silicon Carbide and Boron Carbide are materials with a higher hardness, while having a lower weight, which allows higher end plate solutions to maintain a high threat stoppage level, while keeping a low weight. These materials are inherently more difficult to manufacture/ work with, and are therefore more expensive. Ceramic plates utilizes a strike face composed of Aluminum Oxide, Silicon Carbide or Boron Carbide to break up an incoming projectile. These ceramic materials are incredibly hard, however they are brittle. When a projectile impacts the ceramic strike face, the localized material will shatter, while also breaking up the projectile (due to the superior hardness). All remaining bullet fragments or jacket is then caught by the backing material. The backer and core in a ceramic plate work together to defeat projectiles, a plate cannot work if one is not present. Generally, the pro’s of Ceramics are; its weight, they are generally lighter at around ~6.5-8 pounds, their ability to withstand high velocity AP threats and they do not produce dangerous spall when hit. There really aren't any downsides to a properly made NIJ certified ceramic armor plate. Cracks don't affect performance to a large degree and they do not expire.

2. UHMWPE (Ultra High Molecular Weight Polyethylene) (Or Polyethylene or Dyneema)

For our purposes here, we are talking about PURE Polyethylene plates. Uni-directional Polyethylene as the raw material for plates comes in large long rolls, this material at this state is generally as thin as paper. These sheets are cut to the desired shape of the plate, and dozens of layers are stacked on top of each other and loaded into a heat press with a mold. This compresses the layers together and hardens the material. These plates are generally going to be the lightest rifle threat level 3 or special threat plates available. Pure Polyethylene rifle threat plates are often neutrally bouyant as well. However, that does not come without a cost.

A pure Polyethylene plate can often be defeated by a single round of M855 or 7.62x39 Mild Steel Core. PE plates defeat projectiles by deforming and warping them, much like with PE or Kevlar soft armor. Harder steel core projectiles need at a minimum a thin ceramic layer on the front to help break up and deform the core.

Heat and cold were once an enemy of Polyethylene plates, but generally not any more with advances in UDPE technology. However, extended exposure to moisture AND heat may degrade the performance of the plate over a LONG time by delaminating the layers of UDPE. This doesn't make them useless, just reduces the effectiveness slightly after an incredibly long time in adverse conditions. The NIJ subjects armor to heat and cold chamber torture testing during, however this is short term. Don’t regularly leave your polyethylene plates in harsh temperatures. It will degrade its performance over time. So pure Polyethylene plates are incredibly lightweight, but they come at the cost of steel core protection.

3. Steel armor (AR500, AR650, MIL-A 46100, etc) Steel armor, the cheapest and heaviest of them all. I personally have a strong dislike for steel armor, but I am here to provide facts. How you choose to spend your money at the end of the day is your business, but I will never recommend a steel plate to anyone for any reason. First off there are several types of steel armor, but the properties are going to be roughly the same. Its steel, even if you change the hardness or composition, the fruit isn’t going to fall far from the tree, the physics are similar.

The numbers after “AR”, whether it be 400, 500 or 650 is just denoting the hardness of that type of steel. As you know… harder steel may be brittle, and the other way around it may be soft. MIL-A 46100 is a Mil Spec or “military grade” steel that was designed to be used on armored vehicles or to fortify structures. Let’s start off with the pros of steel since it’ll be short. 1) Can be multi-hit capable. AR500 plates can take a beating, as traditionally they were used as shooting targets. They can be struck in the same place twice generally without issue, or take 30-40 shots.

However this isn't entirely a positive, as repeated strikes in the same general area will blow chunks off of the spall coating, which opens you up to the threat of dangerous lead fragments. Depending on the coating, often a single shot of .308 M80 ball within 2-3 inches of the edge can delaminate the coating. If you are being shot more than 6 times in just your plate, chances are you are being hit elsewhere without armor coverage. Think realistically, do not chase properties that will aid you in unrealistic situations. Now with the cons, 1) Can be vulnerable to high velocity threats such as M193 FMJ.

Level 3 steel plates are vulnerable against FMJ target ammunition such as M193 fired at high velocities (>3000FPS) as well as steel core/ AP ammunition. High velocity FMJ Soft lead core ammunition impacting at high velocities will cause something called shear plug failure, which causes a penetration with a portion of steel breaking off that is larger than the diameter of the projectile that penetrated it. Hardened steel core/ AP ammunition generally has a higher hardness than the steel armor itself, which will cause the penetrator core to bore through the armor.

Projectiles such as M193 FMJ or even .223 Tula FMJ steel case can penetrate AR500 Level 3 with the use of a 20" barrel (M16), however I have heard of instances of barrel lengths as short as 16" penetrating level 3 AR500 plates.

(Video Example, AR500 Lvl 3) https://www.youtube.com/watch?v=oMYkEMhPsO8&t=1s 2) Spalling is a major concern for all steel armor.

Since steel is hard, when a bullet impacts the strike face, it will explode into shrapnel and fragmentation. The spalling that is generated from bullets striking steel armor generally runs laterally along the face of the plate. Which means the most dangerous spalling is going to come from the sides of the plates. Depending on your body position, you could be catching bullet fragmentation in your arms, legs, chin and groin. Imagine throwing a ripe tomato against a wall, bullet fragmentation or "bullet splash" works in a similar manner. The base coating sold with most steel plates is NOT meant to catch fragmentation. The single coating is generally used for corrosion resistance, to protect the bare metal from the elements. The single coating is NOT enough to stop fragmentation. The “Build up coating” option is where you start to see actual spall mitigation. Even then, it is only good for roughly 3 hits in the same general area with 5.56 (can still be spread out) before chunks are blown off and the coating becomes ineffective. Or, often a single shot of .308 M80 ball anywhere near the edge (2-3") will cause immediate delamination of the coating in that localized area and cause dangerous fragments to go into your body.

There are "spall bags" or "fragmentation containment sleeves" made by multiple manufacturers, however most of the time they are actually designed incorrectly. Most of the time they have layers of aramid only on the front strike face. As mentioned previously, the dangerous fragmentation comes out of the edges/ sides. If your aramid does not wrap around the sides, it will not effectively contain fragmentation. Even with material wrapping around the sides, they don't work for dozens upon dozens of rounds, they will fail as well. Of those who do wrap around the sides, they are expensive and your steel plate setup will cost more than ceramics.

Read our standalone article on fragmentation here: https://www.apexarmorsolutions.com/post/bullet-fragmentation-can-kill 3) Ricochets. Ricochets are another concern when it comes to steel armor, if a round hits at an odd angle, it may travel along the plate and go into one of your arms or legs. Due to the hardness of steel, they are more prone to ricochets than Ceramics. 4) Blunt force trauma/ energy transfer Rifle rounds have a tremendous amount of energy and force behind it. Steel is a rigid and hard material, when a bullet strikes it, the energy will “pass through” the steel and into the chest of the wearer. Steel plates should absolutely be worn with a backer (which again, adds to the cost), while most Ceramic plates have them built in. 5) Weight This is an obvious one, a 10x12 Steel plate is 9-9.5 pounds with two buildup coats of spall liner. Then more with trauma padding (seriously shouldn’t wear them without). Steel plates with only a base coating weighs as much as the heavier end of Ceramic plates, but has a level 3 rating and many disadvantages along with it.

Hopefully this article puts to rest some common misconceptions, especially those centered around Ceramic plates. There is a ton of misleading or straight up false information in the armor industry. If you like our information posts, please consider us the next time you decide to purchase armor. https://www.apexarmorsolutions.com/home

Sources:

1. National Institute of Justice 0101.06 Standard: https://www.nij.gov/publications/Pages/publication-detail.aspx?ncjnumber=223054 (PDF) https://www.ncjrs.gov/pdffiles1/nij/223054.pdf -pg. 4 (Level III/ IV testing parameters) -pg. 36 (Drop testing) -pg. 49 (Back-face deformation)

2. MIL-A 46100 D Standard: (PDF) http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-A/download.php?spec=MIL-A-46100D_INTERIM-AMENDMENT-2.020498.PDF -pg. 22 (MIL-A 46100 D .30 cal testing @30 degrees)

3. SAPI/ ESAPI approximate ratings: http://bulletproofme.com/Body_Armor_Accessories_Rifle_Protection.shtml

4. SAPI/ESAPI performance standards: https://www.wikiwand.com/en/List_of_body_armor_performance_standards

Further Reading/ information:

If you’re interested in more of this, here is some more reading to do and some videos.

1. NIJ 0101.06 Standard (One of the sources for this article) https://www.ncjrs.gov/pdffiles1/nij/223054.pdf

2. Shooting test for a Level IV plate: https://www.youtube.com/watch?v=4vL-08x7T4I (Skip to 2:10)