Now, lets discuss;
>What can it stop? Not all body armors are equal?
Body armor effectiveness and protective attributes are generally measured using the NIJ (National Institute of Justice) Rating for Body Armor.
These levels are as follows;
Type I: This armor would protect against (40gr) .22LR LRN at a velocity of 080fps and (95gr) 380ACP FMJ RN at a velocity of 1055fps.
Type IIA: New armor protects against (124gr) 9mm Para FMG RN at a velocity of 1225fps, (180 gr) ..40S&W FMJ at a velocity of 1155fps and (230 gr) .45ACP FLJ at a velocity of 900fps. Conditioned armor protects against (124 gr) 9mm FMJ RN at a velocity 1165fps (180 gr) .40 S&W FMJ at a velocity 1065fps, and (230 gr) .45 ACP FMJ at a velocity of 850fps. It will also stop threats listed in Type I.
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Type II: New armor protects against (124 gr) 9mm FMJ RN at a velocity of 1305fps and (158 gr) .357Mag JSP at a velocity of 1430fps. Conditioned armor protects against (124 gr) 9mm FMJ RN at a velocity of 1245fps (158 gr) and .357Mag JSP at a velocity of 1340fps. It also provides protection against the threats mentioned in Types I and IIA.
Type IIIA: New armor protects against (125 gr) .357 SIG FMJ FN at a velocity of 1470fps and (240 gr) .44Mag SJHP at a velocity of 1430fps. Conditioned armor protects (125 gr) .357 SIG FMJ FN at a velocity of 1410fps and (240 gr) .44Mag SJHP at a velocity of 1340fps. It also provides protection against most handgun threats, as well as the threats mentioned in Types I, IIA, and II.
Type III: Conditioned armor protects against (148 gr) M80 Ball (7.62x51mm/.308) a velocity of 2780fps. It also provides protection against the threats mentioned in [Types I, IIA, II, and IIIA].
Type: IV: Conditioned armor protects against 10.8 g (166 gr) .30-06 M2 AP at a velocity of 2880fps. It also provides at least single hit protection against the threats mentioned in Types I, IIA, II, IIIA, and III.
However, that may not always be the case. The US Military measures it's armor using, MIL-STD-662F V50 Ballistic Test and the UK rates it's armor by HOSDB (Home office Scientific Development Branch) rating.
For the purpose of this discussion and to keep it simple, we'll be utilizing the NIJ Rating for Body Armor.
Generally, two types of armor exists, Soft and Hard. Soft Armor generally is between Type-1 and Type-IIIA protection levels, while Hard Armor are Type-III and Type-IV. Often conically known as “Pistol Rated (Soft) and Rifle Rated (Hard)..
Soft Armor can be made from a multitude of ballistic fabrics (aramids/para-arimids), such as Kevlar, K2, Twaron, ect… that is typically flexible and body conforming. Soft armor with stop the threats it is rated against, but extensive damage can result from Blunt Force Trauma.
This is where “Hard Armor” makes it's intro;
Blunt Force Trauma is the kinetic energy of a projectile transferred onto the surface of the soft armor, with in turn is transferred to the body of the wearer. Blunt Force Trauma can severely damage internal organs, damage veins/capillaries, ect…
Utilizing Trauma Inserts can prevent Blunt Force Trauma. Trauma inserts (aka Trauma Plates) can be made of soft materials (they are not nornally ballstic rated) or hard/rigid materials. Such materials can range from plastics, to ceramics, to rigid fabrics, and to metals.
SAPI/ISAPI (Small Arms Protective Insert/Interm Small Arms Protective Insert) are trauma inserts known as “Special Threat Plates”. More commonly known, simply as “plates”, they're often made of ceramics, metals, rigid fabrics, and plastics…or combination there of.
Some examples are AR500/AR680, Boron Carbide, UHMWPE, Thermoplastics.
Hard and Soft Armor can be worn separately to combat their respective threats they're rated against or worn together, in combination (often hard armor, over soft armor) to provide a form of layered protection. (Plates over vital areas, with soft armor under providing lesser protection over various areas)
So, now that we've established the different types of armor, their threat ratings, and what those armors are typically used for, lets cover….