Strategy Page on the benefits and drawbacks of current body armour options for US troops in Afghanistan and other combat deployments:
The U.S. Army has been trying to reduce the load infantrymen carry into combat. This has proved difficult, no, make that extremely difficult. The problem began with the appearance of, in the late 1980s and early 1990s, of new body armor that offered better protection. The new “protective vest” was heavier and bulkier, thus inducing fatigue and hindering mobility. This often led to battlefield situations where a less tired, and more agile, infantryman could have avoided injury. Military and political leaders usually do not appreciate this angle. But the troops do, as it is a matter of life and death for them.
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Until the 1980s, you could strip down (for actual fighting) to your helmet, weapon (assault rifle and knife), ammo (hanging from webbing on your chest, along with grenades), canteen and first aid kit (on your belt) and your combat uniform. Total load was 13-14 kg (about 30 pounds). You could move freely, and quickly, like this, and you quickly found that speed and agility was a lifesaver in combat. But now the minimum load carried is twice as much (27 kg), and, worse yet, more restrictive.
While troops complained about the new protective vests, they valued it in combat. The current generation of vests will stop rifle bullets, a first in the history of warfare. And this was after nearly a century of trying to develop protective vests that were worth the hassle of wearing. It wasn’t until the 1980s that it was possible to make truly bullet proof vests using metallic inserts. But the inserts were heavy and so were the vests (about 11.3 kg/25 pounds). Great for SWAT teams, but not much use for the infantry. But in the 1990s, additional research produced lighter, bullet proof, ceramic materials. By 1999 the U.S. Army began distributing a 7.3 kg (16 pound) “Interceptor” vest that provided fragment and bullet protection. This, plus the 1.5 kg (3.3 pound) Kevlar helmet (available since the 1980s), gives the infantry the best combination of protection and mobility. And just in time.
[. . .] The bullet proof vest eliminates most of the damage done by the 30 percent of wounds that occur in the trunk (of which about 40 percent tend to be fatal without a vest). The Kevlar helmet is also virtually bulletproof, but it doesn’t cover all of the head (the face and part of the neck is still exposed). Even so, the reduction in deaths is significant. Some 15-20 percent of all wounds are in the head, and about 45 percent of them are fatal without a helmet. The Kevlar helmet reduces the deaths by at least half, and reduces many wounds to the status of bumps, sprains and headaches. Half the wounds occur in the arms and legs, but only 5-10 percent of these are fatal and that won’t change any time soon. Thus since Vietnam, improved body armor has reduced casualties by more than half. The protective vests used in Vietnam and late in the Korean war reduced casualties by about 25 percent since World War II, so the risk of getting killed or wounded has been cut in half since World War II because of improved body armor.