1 –Check out the ballistic material used.
Ballistic vests are made up of multi layers of highly strong fibers which catch and finally deform a bullet like in the shape of mushroom. Because of this act, a large fraction of kinetic energy of the bullet or projectile is spread over the large area of the vest fiber. Some layers may be penetrated but as the bullet deforms, the energy is absorbed by a larger and larger fiber area. Although, a vest stops bullet penetration, but still during this course of action the vest and wearer absorbs the bullet’s impulse to cause blunt force trauma which is numerically expressed in terms of back face signature.
Material like nylon or Kevlar, Twaron or Spectra or polyethylene fiber, either laminated or non-laminated can be used to manufacture bullet proof vests. From these fibers, yarns are made out which are later turned to cloth or panel or fabric by weaving machines. Finally these ballistic panels are then sewn together with shells (cover) and other accessories like straps.
2 – Check out NIJ Rating
National Institute of Justice gives the rating for the body armour the ratings range from IIA to IIIA for soft body armor. These ratings are based on the intensity of the blunt force, exerted by projectile, that can withstand and stopped by the body armor. This is applicable for both stab resistant and ballistic resistant body armor.
The vest whose NIJ standard ratings are: IIA, II, and IIIA come under the category of soft body armors. They are made to stop bullets from small fire arms. These are very lightweight and thinner vests. These three vests are recommended if you are likely to encounter small arms fire. Thus these vests are suitable for civilians who are not in war zone. However, for advanced protection required by soliders in war zone, Level IV vests (hard body armour) are needed.
IIA vests can stop bullets from a 9mm or .40 caliber handgun, II vest can stop 9mm and .357 caliber handgun bullets, while IIIA vest can stop larger caliber handgun bullets like a .357 SIG and .44 Magnum. On other hand level IV vest can save you from .30 caliber armor piercing rounds.
3- Check out legality of owning or wearing B.P. Vests.
It is important that one should be well aware of the local laws or regulations that are associated with the purchase or usage of body armors. Generally, in almost many countries, it is illegal to purchase or wear body armors in the case if the person has been convicted before or has a criminal background. Thus there is a need to abide the local governing rules and get a permit to buy or use such body armors.
- Note down weight and height of the user
- Wear tight fitting clothes (for concealed vest) and uniform (for external vest) for measuring chest or torso sizes.]
- Measure the size of chest and the widest part of torso (while relaxing the muscles and breathing normally). Round off the measured value to nearest whole number. For instance, if the measured size of chest comes out to be 41.1 cm, round off it to 43 cm.
- To get the required length of vest, measure the distance between center of collarbone and navel.
- Compare the body measurements and desired NIJ level with that of the specifications or dimensions given by the manufacturer.
5- Check the comfort
While purchasing the vest by online or offline mode, user is advised to try different physical postures and activity while wearing the vest so as to ensure that the vest is comfortable for the wearer.
Replacement becomes important in every five years or when vest is shot by the projectile as a result of which ceramic plate (in case of HAP) gets cracked or broken. Get a replacement vest every five years or after it gets hit with a bullet.