Troops in Vietnam figured out fast that flak vests were not good for stopping AK rounds, and were better suited for mortar and artillery attacks—hopefully stopping shrapnel—and for sitting on while riding in Hueys during insertions. Most hated wearing them in the bush on patrols due to their weight.
Vietnam-era flak vests were eventually made using ballistic nylon. Some say this material was the Kevlar of its time. The key advantage of the nylon was that it was lighter. It was part of the first generation of ballistic fibers that caught and stopped bullets as if they were in a net.
Ballistic plates
Modern tactical vests, as they exist today, started to come onto the market in the 1980s, in the shadow of the Vietnam War and its enduring lessons. One of those lessons, one also learned back in World War I, related to the existence of the ratio between stopping ability and weight. More stopping ability meant much more weight, a key issue for the infantryman who is always hauling too much weight in his ruck, plus his weapon. Every ounce counts when a grunt is carrying upwards of 80 pounds on extended infantry operations.
Things get a bit technical at this point. Stay with me and I will try to keep it short.
The Army and Marine Corps started putting out bids and doing research in the 1980s, seeking out lighter materials for ballistic plates that provided adequate protection for troops. Materials matter in the construction of most things—cars and trucks, buildings and aircraft—and ballistic plates are no exception. Lighter is better. But no one wants to wear a vest outfitted with soft-butter plates.
Plate carriers were first introduced during this time. Carriers were scalable, or modular, in the sense that plates of various weights and ballistic ratings could be swapped out and switched for lighter or heavier plates, for more or less protection, depending on the situation and the decisions of battlefield commanders. It was also at this time that other materials stared getting looks, such as ceramics, plastics, and fabrics. Each was recognized as having unique pros and cons.
The key to understanding how ballistic plates work is recognizing that they are comprised of fibers, even the ceramic plates. Kevlar was the first material to implement ballistic fibers, which offer about five times the tensile strength by weight. Essentially, when a projectile strikes a steel plate, that plate is trying act like a wall or a shield. A steel plate’s job is to stop the bullet and disperse the bullet’s kinetic energy.
Ballistic fibers work a little differently. When a bullet strikes ballistic fibers, it gets caught in a web of very strong fibers that absorb and disperse the kinetic energy of that bullet. Successive layers of these fibers work together as a multi-layered web. The deformation, or “mushrooming” of the bullet, helps in this. But hardened bullet tips are more difficult to deform and, therefore, to stop. That is the main difference between ball and armor-piercing (AP) rounds.
It was in the 1980s that the U.S. military began rolling out the first PASGT and OTV vests, the first vests to truly offer ballistic body armor protection for troops, beginning the quick progression to where we are today. In part two of this article, we will look at those systems and at the various ratings and levels of ballistic plates, as well as their pros and cons.
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