Always seems like there are big parts of the chest not covered by the Kevlar. I get that there maybe aren’t organs up by your shoulders, but, seems like it makes it easier for bullets to come in from the side. Why not just have more coverage?
In: Engineering
There are lots of body armor that cover the whole chest area with kevlar. The former US military [ Interceptor_Body_Armor](https://en.wikipedia.org/wiki/Interceptor_Body_Armor) is an example of this.
It is modular so you can add arm, neck, leg, and another part to it as required. You can see it cover almost all of the body on [this mannequin](https://upload.wikimedia.org/wikipedia/commons/3/38/USMC_Turret_Gunner_mannequin.JPG)
It has ballistic plates that can protect the front, back, and sides of the torso,
The problem with body armor is that is heavy and not that conformable to wear. It also do not let air or moisture through so you get warm in it and sweat can’t get out.
Kevlar that is flexible can handle bullets from pistols and some fragmentation for explosions but not bullets from intermediate or full caliber rifles. You need stiff ballistic plates for those.
The result is that the level of body armor is a compromise between risk, protection versus weight, comfortableness.
Just protecting the front and back of the chest that can include ballistic plates gives you quite good protection but you can keep the weight down and make them quite comfortable so it is good enough for many situations like the police.
For military usage adding a kevlar that covers more primary is protection against fragmentation from artillery, hand grandad etc that can hit you from any direction. For non-military usage, fragmentation protection is not that relevant because it is not something that is common.
Modern military body armor is historically almost exclusive protection against fragmentation not bullets. Bullets in a military conflict are primary rifle or intermediate caliber that is hard to protect from. Artillery has also been the primary killer in large wars at least since WWI. From WWII you find numbers of 75% of all casualties are from artillery, So this is what military helmets and body armor is primary for.
Heavier body armor that can stop rifle and intermediate caliber bullets have primarily been in military usage for the last two decades in “War on terror” that has been asymmetric warfare ie standing armies vs insurgency or resistance movement militias. The usage of artillery against the standing armies has decrease and small arms or improvised explosives have increased.
Body armory has changed because the primary threat has changed.
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