Do Bulletproof Vests Only Work Once? The Real Answer

Are you thinking of buying a bulletproof vest?

News flash: Nothing can be 100% bulletproof. In some rare cases, a bullet can pass even through a vest that’s designed to stop it. So, the right term to use is a “bullet-resistant” vest.

Even so, bulletproof vests do provide some protection depending on the design and save your life.

So, do bulletproof vests only work once?

In most cases, the answer is yes. Ideally, soft and ceramic body armors should be replaced after a single bullet strike. However, some polyethylene armors can take multiple hits. It also depends on the type of vest you’re using. Some manufacturers recommend replacing the vest after a single bullet hit. Others claim that their products can take multiple hits. 

For a proper understanding, you need to take a look at how bulletproof armors work and the various material types.

In this article, we will take a closer look at bulletproof vests and their design.

Let’s dive in.

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How Do Bulletproof Vests Work?

Knowing how bulletproof vests work will help you to choose a product that best serves your purpose.

The idea of a bulletproof vest has been around for a long time. The Italian and Roman royalty experimented with it in the 16th century. The Japanese developed a type of bulletproof vests with silk in the 19th century. During World War II special jackets made from ballistic nylon were used.

In the 1970s, the history of bulletproof vests entered a new chapter as DuPont’s Kevlar ballistic fabric was invented.

With time, special materials like aramid and high-performance polyethylene (HPPE) were used in bulletproof vests. Both these materials have a high strength per weight ratio as well as high stiffness. A few other varieties of bulletproof fibers are Spectra, Dyneema, and Teijin

During manufacturing, the materials undergo a special spinning process while they are still viscous. The process orients the molecular chains along the longitudinal direction of the fibers. This improves the ballistic performance.

The fibers are woven together to form panels or plates that form the basic structure of a bulletproof armor. With more layers, the fabric structure gets thicker and tougher. Hence it offers better protection against larger rounds.

While aramids are generally used in soft body armors, materials like ceramic are used in hard body armors.

In general, concealable body armors or soft armors provides protection against low and medium energy rounds from a handgun. For protection against heavier rifle bullets, armors with semirigid or rigid construction are required. 

What happens when a speeding bullet comes in contact with the armor?

The armor material absorbs the impact and the energy of the bullet is distributed across the entire plate or the densely packed fibers. After the impact, the bullet spends its energy and gets deformed or “mushroom”. 

Actually, the layers reduce the supersonic- above sound speed- velocity of a bullet to subsonic levels. This gives the fibers more time to absorb the energy and reduce the force of the bullet. 

You will still get an ugly bruise from the bullet impact. But, since the energy of the impact gets dispersed, the internal organs are protected from serious injury.

To put it another way, it’s like wearing boxing gloves. The force of a punch is reduced as the glove absorbs the impact. Besides, it also protects your hands from damage.

Consider a semi-automatic rifle like the AR-15. A bullet from the rifle can travel at a speed of around 3,300 feet per second, which is much higher than the speed of sound. That means a thicker armor will be needed to stop this bullet.

By contrast, a 9mm round from a pistol can travel at the speed of 984 feet per second. That makes it relatively easier to stop.

To stop rifle bullets, special armors come with metal or ceramic plating. These plates shatter the bullet in order to absorb its energy. Since they are heavy and bulky, these armors aren’t suitable for law-enforcement teams on patrol. They are mostly used in special tactical situations for short periods. 

Basically, bulletproof vests are categorized into various types depending on the level of protection they offer. These specifications are set by the National Institute of Justice (NIJ)

It goes without saying that a vest designed to resist small ammunition fire will not protect you from larger rounds. So, the type of armor you need will depend on the situation and the dangers you are facing.

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What are the types of Bulletproof Vests?

Presently, the body armors are classified into five categories by the NIJ. These are Level IIA, II, IIIA, III, and IV. The level I rating is considered obsolete at present. 

While level one armors offer the lowest resistance, level four armors offer the highest. All bulletproof vests undergo stringent protection testing as per the guidelines set by NIJ.

The first three types are classified as soft armors. The remaining two types are hard armors designed to offer protection against rifle bullets.

Here’s a look at the various bullets that these armors protect against.

Type IIA– 9mm FMJ RN; .40 Smith and Wesson(S&W) FMJ

Type II– 9mm FMJ RN; .357Magnum JSP.

Type IIIA– .357 SIGFMJ FN; .44 Magnum SJHP

Type III– 7.62mm FMJ (M80) (Rifle).

Type IV– .30 Cal AP (M2 AP) (Rifle).

Keep in mind, the threat from a bullet depends upon its design and the speed of travel. The bullet size (caliber) and the weight are also important factors. However, two bullets of the same weight and caliber can have different impacts on a vest depending on their design and material.

Round nose or hollow point bullets expand on impact. But rifle bullets with pointed tips can pass through soft armors. This is why hard armor plates are needed to stop them.

Bullets also come with a full metal jacket or are semi-jacketed. These give them a higher velocity. Special armor-piercing bullets are jacketed and come with a steel or tungsten core that makes them harder.

What are combination armors?

These are special armors that are designed to offer protection against bullets as well as stabbing attacks. These vests contain special layers that provide protection against stabbing and additional layers that offer ballistic resistance. They are also called multiple threat armors.

Beyond that, there are In-Conjunction (IC) armors. These armors are made of soft panels with special pockets in the front and rear. Hard armor plates are inserted into these pockets for extra protection.

What are the Materials Used for Bulletproof Vests?

Time to take a look at some of the common materials used in body armors.


Steel is one of the oldest materials used as armor. Moreover, it’s cheap and also has more durability than materials like ceramic. A46100 steel offers excellent toughness and can provide protection from a bullet traveling at 3,200 feet per second. This steel is used in body armor as well as in manufacturing armor plating for military vehicles.

However, steel is heavy and not flexible. So, it’s not possible to shape it into a comfortable vest. Bullets traveling at higher speeds can penetrate through a steel plate and cause serious injury.

In addition, bullets can also bounce off a steel plate and change direction. The ricochet can cause serious injuries to the unprotected parts of the body.


Ceramic is a non-metallic material, that has excellent hardness but is brittle in nature. However, modern armors use ceramic composite that contains boron carbide. In the Mohs hardness scale, boron carbide measures between 9 and 10. It’s one of the hardest substances on the planet.

Beyond that, ceramic is lighter and is better at absorbing the energies of a speeding bullet than steel. This also makes it effective against special supersonic armor-piercing ammunition.

On the downside, it’s expensive and requires more care. Due to the brittleness, it can shatter from a bullet impact or can develop cracks. So don’t expect a ceramic plate to withstand multiple bullet impacts.


A special category of polyethylene, Ultra-High-Molecular-Weight Polyethylene  

(UHMWPE) is one of the most popular choices for making body armor. This is due to its low weight and ‘’ultra-high-molecular-weight’’. 

Since it’s thermoplastic, it has excellent chemical inertness and is more abrasion-resistant than steel. It’s a very hard-to-break material and isn’t easily eroded. Another great feature of the material is its low friction coefficient. That means it slides very well and can move freely. It is also not affected by water.

However, UHMWPE is vulnerable to high temperatures. Above 80-degree Centigrade, the performance falls rapidly. Also, UHMWPE is used only in top-grade bulletproof vests. So, you can expect it to be expensive.


Aromatic polyamides or Aramid is a special synthetic fiber with excellent mechanical properties and high heat resistance. Their molecular structure consists of rigid polymer chains that make the material extremely durable. Since the material is flexible and lightweight, it can be used effectively to make soft armors. 

The commonly known Kevlar material is chemically called poly-paraphenylene xerophthalmia and it’s an aramid type fiber. Another commercial form of Aramid commonly used in bulletproof vests is Nomex. 

The molecular structure of Kevlar is formed from chain-like bonds between hydrogen, carbon, oxygen, and nitrogen. The material has high tensile strength both along with the chain structure and perpendicular to it. The tightly woven fibers of the material can steal a lot of energy from a bullet.

Aramid materials have two major cons. Firstly, they are vulnerable to UV radiation. Next, they can absorb water and degrade.

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How Many Shots Can a Bulletproof Vest Take?

In most cases, manufacturers provide a detailed insight into how many rounds an armor can take. This is done in line with the armor testing parameters set by NIJ.

That means the life of the armor can vary based on the armor type and design.

In general, armors need to be replaced even after a single strike. It’s possible, the deformation of the fabric after a single shot isn’t visible under the naked eye. This can affect its ballistic performance. 

And if you’re really unlucky, the second round might hit the same damaged spot caused by the first round.

In some cases, hard plated armors require replacement even if they are accidentally dropped.

The reason a drop can break materials like ceramic or develop microcracks. This can affect its performance.

On the other hand, some manufacturers claim that polyethylene armor plating can stop multiple rounds. The material melts due to the impact of the bullet and then re-hardens. Thus, it retains its ballistic integrity even after multiple impacts.

In addition, soft body armors may need replacement if they are stretched or deformed. Kevlar armors often need replacement if they get wet. Kevlar can also get degraded when it comes in contact with salt- more specifically, sweat. In these cases, the material fibers can weaken and decrease the armor strength. Armors made from PE materials can weaken after prolonged exposure to UV rays.

As per NIJ specifications, a body armor needs to be replaced after five years, even if it hasn’t been impacted by a bullet even once. 

What it means is this…

In case you’re planning to buy an old or used vest, don’t. Once the fabric of the vest is damaged, it can’t be repaired.

To sum up, it’s always best to replace an armor after it has absorbed a bullet impact.

How to Maintain a Bulletproof Vest?

Maintaining a bulletproof vest in the right manner is extremely important if you want to prolong its life. In fact, care and maintenance of the vest are often considered more important than its age for preserving ballistic resistance.

Note, the common things that affect the fibers of a bulletproof vest are wear and tear use of harsh cleaners and soap residue, improper storage, and exposure to moisture.

Here are the main points that you need to take note of while storing a vest.

  • Inspect the vest regularly for any cuts or tears. Check the panel seams and ensure that there’s no separation of the fabric or the stitching. The plates should be inspected for any surface cracks. In case there are any creases or folds in the armor, it can be a sign of a weak point in the material.
  • Body armors should be stored properly after use. Most manufacturers suggest that the vest should be stored flat to preserve its quality. Make sure not to put any heavy objects over it. Also, hanging the material can result in the carrier straps getting stretched. This can affect the fit in the long run.
  • Cleaning the body armor is extremely important as well. This will also prevent odors and mold development. The material should be hand washed in cold water and dried indoors, away from direct sunlight. Don’t machine wash or use any harsh chemical cleaners unless specified by the manufacturer. The panels can be cleaned with a wet sponge or soft cloth, and then air-dried.
  • Don’t store the armor in a place where there’s low airflow for long periods. It should also be kept away from direct sunlight and high humidity as much as possible.

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How to Choose the Right Body Armor?

The first point to consider is the level of protection that you need. Depending on that, you can select the body armor type.

Next, the fit and feel of the vest need consideration. One common reason that prevents officers from using armors regularly is the fact that they are bulky and uncomfortable. So, flexibility and mobility have become important factors in armor design. This is more important when you are using a concealable vest.

The reality is, even if two people have the same height and weight, they may need different vests. 

Why so?

Actually, the ratio between the length of the torso and the legs can vary between people. This makes the vest sizes different.

Quite simply, if a vest doesn’t offer a comfortable feel, it will be left behind by the user. When it is not worn, there’s no question of offering life-saving protection.

Depending on your body shape, you can choose a standard-sized vest or one that’s specially customized for your fit. While the customized fit is the best option, not all brands offer this choice for buyers.

When choosing a standard dimension, the main measurement points are around the waist and the chest. Apart from that the front of the vest while sitting and standing and the back length are also considered.

As per some experts, a third dimension should also be considered while picking a vest. This is the measurement from above the belt from the front side to above the belt in the back. This measurement allows for a snug fit of the armor with minimum gaps.

The weight of the vest is another important factor while choosing. It’s best to check the comfort and wearability of a vest before buying. At times, a vest with a slightly higher weight might feel more comfortable due to the materials used and the design.

If you lose or gain weight, change the armor. Body armor with an improper fit will not provide the right level of protection.

Overall, choosing a bulletproof vest that fits well is equally important as choosing the right category.

Do Bulletproof Vests Really Work?


Bulletproof vests designed as per NIJ specifications definitely offer protection from the specified type of bullets. Without a doubt, it’s a critical piece of protective equipment.

While accurate estimations are not possible, bulletproof vests have saved thousands of lives since their introduction in law enforcement in the 1960s. As per one report, an officer shot while wearing a bulletproof vest is three times more likely to survive a bullet than without the protection.

However, there have been fatalities when the armors were penetrated by bullets of higher power than NIJ bullet protection ratings. In some other cases, officers were injured when the bullet struck areas of the upper body not protected by the vest. One common vulnerable spot is under the arms when the arm is raised.

But as we already mentioned, no vest offers total protection from a bullet.

Actually, the slower the bullet, the better is the protection of a vest. That means you are more protected from a .44 Magnum than a .357 SIG.

Final Words

In general, it’s best to replace a bulletproof vest once it has been struck by a bullet. However, you can check the details provided by the manufacturer before making a decision. Keep a lookout for any signs of damage that may indicate that your armor needs replacement.

Before you choose a bulletproof vest, make sure that it offers the best possible comfort, durability, and mobility. At the same time, assess the dangers to ensure that you choose the right type of vest.

Can you really afford not to?


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