What will stop a bullet?

The arms race between offensive weapons and defensive armor has spanned centuries, and with the advent of the firearm, so has the quest to find the most effective and efficient bulletproof materials. A combination of innovations and accidental discoveries have led to the development of modern bulletproof materials like Kevlar and UHMWPE (ultra-high molecular weight polyethylene). However, those who want to be prepared for future situations where they might not have the opportunity to don body armor may want to consider the benefits of proper cover and the types of materials capable of protecting them.

Relying solely on armor like bulletproof vests may not always be an option, particularly when you’re caught unaware. It's crucial to understand that not all materials are created equal, but anything capable of rapidly decelerating a bullet or stopping it outright is considered "bulletproof." Thin corrugated sheet metal and wooden planks, for example, are far from effective at stopping bullets. In fact, wooden barriers can shatter upon impact, sending bits of wood flying at whoever was unfortunate enough to choose the wood for cover.

Steel, however, with its exceptional strength and durability, was one of the earliest materials used for bulletproofing. In the early days of firearms, steel armor was effective at deflecting low-velocity musket rounds. However, as bullets evolved into the powerful centerfire cartridges of the modern era, steel had to become thicker and heavier to provide adequate protection. This made it impractical for armor, particularly for personal use.

Contrastingly, earth or tightly packed sand can be remarkably effective at stopping bullets. Sand, for example, can absorb over 85 percent of the energy exerted against it, its resistance increasing with projectile speed. This means that sand can outperform even steel when it comes to absorbing ballistic impacts. If you're ever in a situation where you need to fortify your home, consider filling your barriers with sand.

I say this because the walls of modern American homes are not normally rated to stop bullets. Small caliber pistol ammunition has been known to penetrate the cheap, thin walls characteristic of American architecture, as was demonstrated in a recent incident in San Antonio in July 2023. A man who was doing nothing but lying in his bed was shot through the walls by a shooter who was seemingly attacking apartments at random. In the same way, another victim was killed in May of the same year when his next door neighbor was modifying his loaded weapon and accidentally fired it through the wall. This highlights the importance of understanding the limitations of common construction materials.

When it comes to bulletproof construction materials, the ballistic resistance of concrete largely depends on its thickness. A solid 4-inch section of wall can effectively stop bullets ranging from .40 S&W to .308, while a 6-inch brick wall reinforced with 4 inches of clay can withstand even .50 caliber rounds.

However, when it comes to protecting the human body, we need materials that offer high tensile strength while remaining lightweight and flexible. This is where UHMWPE and Kevlar enter the scene.

UHMWPE, or Ultra High Molecular Weight Polyethylene, derives its strength from its unique molecular structure. Its long, overlapping molecular chains provide enormous tensile strength, making it an ideal material for bulletproof applications. In comparison, Kevlar derives its strength from numerous short inter-chain bonds. Both materials have revolutionized personal protection.

Kevlar, accidentally discovered by the Dupont tire company, is seven times stronger than steel, while UHMWPE takes it a step further by being fifteen times stronger than steel. In fact, UHMWPE holds the distinction of being the world's strongest fiber, and the material used in BulletSafe bulletproof vests.

The pursuit of bulletproof materials has come a long way from the days of heavy steel armor. Today, innovative materials like UHMWPE and Kevlar provide lightweight, flexible, and incredibly strong protection against ballistic threats. As technology continues to advance, we can expect further breakthroughs in materials science, pushing the boundaries of what we consider "bulletproof." In a world where personal safety is paramount, the evolution of these materials brings us one step closer to a safer and more secure future.