How Do Bulletproof Vests Stop Bullets

How Do Bulletproof Vests Actually Work?

What Are Bulletproof Vests Made Of?

Bulletproof vests are articles of personal armor that are worn to reduce impact, prevent damage, or otherwise prevent penetration of the body from a projectile (bullet, shrapnel, explosives, etc.). So it is imperative they are made out of incredibly strong materials; However, before going into the materials, it is important to mention that ‘bulletproof’ vests are technically only ‘bullet-resistant.’ Additionally, many bulletproof vests starkly vary in effectiveness. The first bulletproof vests were crude and often made of thin layers of metal intended to deflect bullets. Silk was used for some Japanese armors and ended up a great material for deflecting low-velocity bullets. Flak jackets were introduced during the second world war and were made out of ballistic nylon. Flak was mostly ineffective against actual gunfire, but still made soldiers feel safer in battle.1

True bullet-resistance was discovered in the 1960s, which would lead to the introduction of the Kevlar vest a decade later. The first Kevlar vests proved very effective, reducing the lethality of nearly 95 percent of .38 caliber impacts. Today, there are bulletproof vests made of High Tensile Strength fibres, as well as Ultra High Molecular Weight Polyethylene (UHMWPE).2There is also graphene, which is relatively new but has been proven to be stronger than Kevlar. Graphene has yet to become reasonable to commercially produce, as it requires extremely high-intensive manufacturing techniques and is still an expensive material.

How Do Bulletproof Vests Actually Work?

Depending upon the material, a bulletproof vest is going to respond differently to the impact of various bullets. UHMWPE, for example, is ultra strong and used for a variety of industrial applications. It is also used as a steel liner-replacement in tires. Higher quality vests (such as Level IIIA, and Level IV) are typically able to withstand any .44 caliber bullet or weaker, from rifle or handgun. These vests are normally made of various materials, including both extreme fibres (as mentioned), and metal plating [steel], ceramic, or even Dyneema.2The metal plating is sincerely vital if there is a risk of rifle fire.

When metal is worked into a vest, the usual purpose is to deflect a bullet. Whereas fibres are meant to trap a bullet. Fibres work by slowing down the velocity of the bullet as it works through each layer of the fibres. The increased surface area all of the fibres help diffuse the bullet’s energy. Kevlar, for example, is a super high-strength polyarylamide fibre. It is woven so tightly and in so many layers that the bullet is forced to slow down as it attempts to press through the fibres. Even though Kevlar and Dyneema are technically both plastic materials, they are such strong materials on a molecular level, that they take a ton of energy to stretch. This type of tautness makes for a wonderful bullet-resistant material.

Many body armors which are based on a fibre material, like Kevlar, will spin many of the threads together, creating a yarn-like material. These thicker weaves of the strings are then stitched together into sheets and combined into layers.3As previously mentioned, some of these sheets are also outfitted with metal or ceramic plates. Even in the top-grade soft armors, so many fibres exist that the energy of the bullet cannot exceed the surface area of the tightly interwoven strands. The bullet’s energy ends up dissipating outward and to the sides, rather than through and into the target.

Are Bulletproof Vests Effective?

Even after understanding how the strands of fibres work in a bulletproof vest, one may still find themselves asking “Do Bulletproof Vests Actually Work?” The answer is absolutely yes! Bulletproof vests work in the sense that they are made to resist bullet piercing and they are highly effective in doing so when the appropriate vest is selected. The better vests on the market have all been tested thoroughly to ensure they can withstand the necessary impacts. After the caliber rises above .44 or the bullet is fired from a rifle, however, most bulletproof vests (and thus the target) will become much more vulnerable.


1Bullet Safe. The History of Bulletproof Vests. Retrieved from:

2Bullet Safe. Bullet Proof Vest Materials. Retrieved from:

3Body Armor News. How Does Kevlar Work? Retrieved from:

About the Author:

Mark Doberman, The Proprietary Gun Smith

The Proprietary Gun Smith is a marksman, expert gun handler, ammunition specialist, survival guru, and lifetime gun enthusiast. He owns (or has owned) nearly every legal firearm and ballistic available, has fired nearly every gun, and regularly consults professionally in the firearm world. He has studied firearms and similar tactical lifestyle for more than 40 years. In addition to writing for, TheProprietaryGunSmith has guest written for more than a dozen other sites and/or magazines in the industry.

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