Armored Republic Body Armor Glossary
Use our Body Armor Glossary from Armored Republic to learn about common body armor and ammunition materials and terms.
Common Armor Materials
Aramid
Most have heard of the main brand version of this material; Kevlar. Kevlar is a registered product of Dupont plastics and was the first to blaze the soft armor trail. Aramid has been and will continue to be one of the best soft armor materials available in terms of cost and performance. The shelf life of aramid, given the plastic fiber's ability to negate its prolonged exposure to salt (sweat) and UV from the sun, is much shorter than steel at only 5 years. Aramid has been around much longer than some may know. Its original usage goes as far back as WWII in the form of the Flak Vest. These vests were issued to aircrewmen of the Royal Air Force to protect them from their main threat at the time: German AA guns firing flak canisters.
Fun Fact: Aramid fibers have to be behind any ceramic strike face to prevent spalling and are the primary reason for the armor's low shelf-life. Aramid also has a high resistance to heat and is the primary material used in firefighters' protective jackets.
Carbon Fiber
This is a more common material that most are familiar with. Carbon fiber was briefly used as armor in the form of a carbon fiber nanotube. Nanotubes are tiny filaments of carbon that can be woven, effectively giving you a soft armor material with the strength of carbon fiber. When this is layered it provides excellent ballistic resistance. This material never saw widespread usage for 3 reasons:
- It was expensive to produce
- It couldn’t be printed in long enough strands to make large sheets of armor
- There were potential respiratory and endocrine safety issues due to the small particles of carbon fiber
Fun Fact: In the 80s and 90s, carbon fiber was employed alongside titanium as trauma plates (not to be confused with trauma pads) in early police soft armor carrier setups. These plates helped prevent fatal backface deformation and sternum notch collapse in early soft armor vests when facing magnum cartridges.
Ceramic
Ceramic is a good material used for armor applications, however, not all ceramic is capable of ballistic protection. Ceramic plates used in this capacity are usually sintered (the process of forming and compacting a solid mass of material by pressure or heat without melting it to the point of liquifying) with alumina, boron carbide, silicon carbide, and/or titanium diboride. Ceramic has a surface hardness close to a diamond and is capable of breaking up most projectile compositions (lead, copper, brass, steel, and tungsten) at the expense of breaking itself apart in the process. This means Ceramic is capable of stopping threats steel and other armor materials are not able to address. For example, ceramic armor is capable of breaking up tungsten carbide armor-piercing rounds. As with anything that has an increase in surface hardness, its ability to flex is almost non-existent. This means most ceramic plates break when shot, are not multi-hit rated, and are susceptible to breakage from rough handling.
Fun Fact: Ceramics' first operational use during combat was in the Vietnam war. It was issued to helicopter crews in 1965 to aid in incoming small arms fire.
Composite
This is a generic term that will usually refer to more than one material used in an armor plate/panel composition. This can loosely refer to ceramic and its soft armor backer, PE (polyethylene) plates with a fiber backer, or a hybrid-armor type like steel and PE, or ceramic and PE. Whenever you see the term “composite armor”, always make sure to see what the components of the composites are.
Fun Fact: The military uses the term “composite armor” specifically in relation to vehicle armor employment. It not only refers to multiple materials used but proper spacing and staging of the materials to optimize protection.
Polyethylene
Ultra High-density Molecular-Weight PolyEthylene (UHMWPE) or PE armor, for short, is a long chain, high-strength, low-wear type of polymer. It is used in any application where lightweight and high strength are needed such as in joint and hip replacements, competition boat sails, tear-resistant ropes, cut-resistant gloves, and of course body armor. PE is ultra-lightweight as the name implies. For example, our P2 plate weighs only 3.3 LBS while being rifle rated up to Level III or 7.62x51 @ 2780 FPS. This material stops projectiles by creating friction after smashing out a projectile, heating up, then re-hardening around the projectile as a resin. Due to this process, this armor type is only capable of defeating lead and copper type projectiles while mild steel core penetrator rounds can make their way through. This armor shines when used in combination with another armor type to help defeat steel penetrator ammo or by itself when the absolute lightest weight rifle protection is needed.
Fun Fact: UHMWPE, originally branded as Dyneema, had its first recorded use in 1992 in a yating competition called the “America Cup” by the boat America³ (pronounced America cubed). America³, which won the competition, accredited the win to the lightweight, high-strength sails made of Dyneema.
Steel
Steel is another excellent material used in armor applications - when done correctly. Due to a massive variation in steel blends that meld surface hardness and flexibility, there is a “goldilocks zone” that most steel blends need to be at to be practical for protection usage. If the steel is too hard, it will fracture like ceramic when hit. Likewise, if the steel is too soft, it is penetrated too easily. AR500 and AR550 high carbon steel are one of the most practical combinations of flex and surface hardness.
Fun Fact: AR500 Steel is an evolution of the steel employed on the Sherman tank's main hull armor in WWII (1941), known as MIL-A-12560. The primary difference is that the AR500 is now stronger and lighter.
Titanium
Titanium (or Ti, and not to be confused with the ceramic-titanium diboride) is an alloy that boasts attributes such as being harder than steel and akin to aluminum in weight. While this may seem like an obvious choice when it comes to using alloys as armor, Ti has some attributes that generally make it unfavorable when compared to steel. The first issue with Ti is its hardness. Because the material is far harder than steel, Ti is far more prone to stress fracturing when hit. Moreover, with stress fracturing, you get spalling. This means when Ti is used in an armor capacity, it requires some form of protection like soft armor behind the plate similar to ceramic armor. On top of the stress fracturing and subsequent spalling, you also get projectile fragmentation off the surface of the plate that is akin to bare steel usage. This means all Ti armor must have some form of fragmentation AND spalling mitigation coating or there is a risk of secondary injury. The last and final nail in the coffin of Ti armor is cost and availability. Most of the world's Ti supply comes from Russia, and even if availability is not an issue, the sheer cost of working with and cutting Ti can be astronomical.
Fun Fact: As noted with availability, Russian body armor systems are far more prone to using Ti in both body armor and helmet capacities. Extensive testing of Russian armor has shown Ti is inferior to steel as an armor material.
Alloy
An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of metal in the resulting material, such as electrical conductivity, ductility, opacity, and luster, but may have properties that differ from those of pure metals, such as increased strength or hardness.
Fun Fact: All steel is an iron-based alloy. The other components in the alloy mixture ultimately determine its strength and are the reason why not all steel is suitable for armor usage.
Common Armor Terms
SAPI - (current meaning) Small Arms Protective Insert. This is the technical name for the hard armor issued by the DOD. The current iteration of the issued SAPI is the ESAPI or XSAPI plate.
SAPI - (former meaning) Stand Alone Protective Inserts. A majority of police departments in the late 90s or early 00s were issued armor in the I.C.W. type (see below). The term SAPI informally can refer to the change from I.C.W. type armor to a standalone type.
I.C.W. - In Conjunction With. This refers to multiple armor types that need to be used in conjunction to achieve a threat-level resistance. Most frequently, this refers to a plate and a soft armor backer. For example, all Level IV ceramic plates need to have a soft armor backer to catch spalling. Keep in mind there are standalone ceramic plates like those we offer, however, ESAPI-type plates issued in the DOD need to have a separate piece of soft armor in the plate pocket behind them to achieve the same threat level as a standalone type.
Angle Strike - Also referred to as a glancing strike or glancing blow. This refers to an armor plate being hit at an angle more extreme than 0 degrees from the weapon facing the plate's strike face. Despite common misconception, angle strikes are easier to stop because the material in a plate when faced at an angle is thicker than at 0 degrees and the angle of the hit can cause the projectile to travel towards the path of least resistance and ultimately off of the intended flight path of the projectile. Angle strikes are far more common with helmets than rifle plates given the conical shape of a helmet.
Edge Strike - An edge strike is when a projectile hits the edge of a plate. Most armor materials require a surface hardness AND a distribution of surface tension. This means not only does the material have to be hard enough to stop the projectile, it has to be robust enough in surface tension to prevent a weakness in the material from causing a deformation. For materials like PE and ceramic, edge strikes can lead to penetration as the surface material ends at the edge of the plate. There isn’t enough surface tension to keep the material of the plate from folding or flexing into you - effectively redirecting the projectile into the wearer. Steel is the only armor material that will naturally prevent an edge strike penetration due to its hardness and structural makeup.
Plate Carrier - A plate carrier is an article of fabric clothing that, depending on the usage, will go underneath or on top of your clothing to hold armor plates against your vital organs. It can be referred to as a Vest, Kit, Rig, or Flak. Keep in mind that these terms are typically used loosely to not only denote the carrier but also to denote the armor system used in conjunction with the plate carrier. Plate carriers DO NOT provide any ballistic protection by themselves. They are simply a catalyst to hold armor against your body. The protection you will get out of a plate carrier will solely depend on the armor plates or panels that have been put into it.
Cummerbund - Cummer what? This is a term that at one time was associated with formal dress wear. A cummerbund, in this context, is a band or lateral support system that stays affixed to the backside plate pocket of a plate carrier and will attach or disconnect from the front side plate pocket. Cummerbunds are intended to do 2 things:
- To provide additional plate carrier stabilization; preventing the carrier to shift when it is worn
- To provide additional external MOLLE webbing, which allows for the mounting of additional pouches.
Make sure to disconnect your cummerbund before putting your carrier on, then resecure it so your plate carrier fits you like its custom fit every time you put it on.
Shoulder Strap - Like the cummerbund above, the shoulder strap is a structurally integral component to provide plate carrier stabilization while wearing armor. Shoulder straps do a few things:
- They link your front and rear plate pockets together. Most shoulder straps are fully adjustable, allowing you to program how far down your plate drape is. Shoulder straps more often than not also have a quick-release feature in the form of a buckle or cord that when pulled or disconnected will allow the carrier to be removed quickly.
- Most carriers will employ a shoulder pad that goes over the shoulder strap. Given this is a high tension load-bearing area, it is generally recommended that shoulder pads be used, especially for long periods of rifle-rated armor usage.
Fragmentation - Also known as Frag, happens when a larger object becomes smaller particles that propel in an outward, unidirectional pattern. This can usually happen in 1 of 2 ways either velocity or explosive. When a high-velocity projectile hits a hardened surface with enough speed, it will implode on itself, causing outward redirection. This is seen when a bullet hits a hard surface like steel, ceramic, aluminum, or glass. The second way fragmentation is produced is by means of an explosive charge inside a hardened object, that blows the object apart into smaller pieces, such as seen in a hand grenade and explosives.
Plate Pocket - The plate pocket is the portion of the plate carrier that holds both the front and back portions of the armor insert. The pockets are also commonly denoted as “Front and Rear” plate pocket(s) to identify what portion of the carrier is the front and what portion is the back. In an outer carrier, the external material of the plate pocket will be where the MOLLE webbing is stitched to. Sidenote: A quick way to identify the difference between front and back plate pockets is: Most back side plate pockets have a drag handle and ALL back side plate pockets will be the section of the carrier that the cummerbund is permanently affixed to.
Drag Handle - Possibly the most overlooked and vital portion of a plate carrier, the drag handle is meant to pull you out of a bad situation. The drag handle is located on the back side of the plate pocket on a plate carrier and its intended purpose is to be a reinforced area where a teammate can pull you off the “X” if you have been downed. Although drag handles are absolutely vital, their shape, material, stitch pattern, and effectiveness can vary greatly depending on the design. Some drag handles pull out and become an extended leash allowing better leverage while others are simply small “U” shaped pieces of fabric with reinforced stitching. In any event, under normal circumstances, you will never need to use a drag handle until you or a teammate are in a bad situation and need to be pulled out of the line of fire.
MOLLE - MOdular Light-weight Load-carrying Equipment. We know, the military has an odd way of creating acronyms. Molle refers to the fabric ladder system stitched horizontally on outer tactical vests and plate carriers along with the back side of pouches that mount to them. It's an interface system that allows you to add and remove pouches to your plate carrier for gear storage.
Spalling - Or spall. This refers to the parts of a stationary object like an armor plate, that when hit by a high-velocity projectile, break pieces of itself off. These pieces then become hazardous projectiles themselves. This term was originally associated with tanks, as a tank's armored hull can become lethal to the crew inside when penetrated, even by a small projectile. Today this is most commonly associated with ceramic armor and its breakage when shot.
BFD - Backface Deformation. This is a term that refers to the amount of deforming or mushrooming the backside of an armor plate or panel will incur. The established maximum backface deformation is no more than 44 mm.
Trauma Pad - A trauma pad is a soft or preferably non-newtonian material pad that goes behind your armor plate and in front of your body. Its sole function is to mitigate BFD - reducing the amount of force transferred to the wearer. Trauma pads can also be used in plate carriers that do not have padding to further enhance comfort while wearing and donning/doffing.
Trauma Plate - A trauma plate (not to be confused with a trauma pad) is an antiquated method for preventing backface deformation. In the 80s and 90s soft armor was not at the same level of manufacturing precision as it is today and it was not uncommon for magnum handgun calibers to still be lethal even if the bullet was stopped by the vest. A trauma plate was a carbon fiber or titanium plate, usually about 2” to 4” that rested on top of your soft armor in a special pocket that positioned the plate directly over your sternum. Current manufacturing techniques have allowed mitigation of backface deformation that has negated the use of trauma plates altogether.
Body Side - This is a marking found on most armor plates. It denotes the side of the armor that needs to be facing your body.
Blunt Force Trauma - The force or trauma inflicted on a person caused by backface deformation (BFD).
Bulletproof - A slang term used to refer to ballistic protection. Nothing is bulletproof. With enough firepower, mountains can be leveled.
Caliber - The diameter measurement of a bullet. This is expressed in hundredths of an inch or mm. For example, a 9MM bullet has a 9mm external diameter and will make a 9 mm-sized hole in something it penetrates. 9MM when converted to standard measurement becomes .380” / 1.00”. A 45 caliber bullet is .450” / 1.00” or 11MM.
Conceal - To hide. This is referring to concealable type armor such as our concealment soft armor carrier. This armor is for stealth and EDC usage.
Glancing Strike - See Angle Strike.
OTV - Outer Tactical Vest. This is a term generally used to describe a plate carrier with external molle webbing used on top of any clothing the operator may be wearing.
SPCS - The Soldier Plate Carrier System. This is the current plate carrier fielded by troops in the US military. This carrier has a stark comparison to the IOTV, the previously issued armor type. This current carrier shows the ARMY has shifted its focus on protection where it’s needed and mobility where it’s not.
Kit - A slang term for a plate carrier, plates, and pouches all configured and ready to go.
Rig - A slang term for a plate carrier, plates, and pouches all configured and ready to go.
Multi-Hit - This is a term that refers to an armor's plate capability to take more than a single hit. Most plates on the market can do this, however, there is often no way to measure exactly how many given the variables.
NIJ - National Institute of Justice. A body that is paid for certification and independent testing of body armor. They established testing standard 0101.06 and the proposed 0101.07 that most body armor companies conform to when manufacturing armor.
Strike Face - The opposite side of “Body Side” - denotes the face of the plate that goes outward and makes contact with any incoming projectile.
Common Ammunition Terms
AP - Armor Piercing. This refers to a projectile that was designed with the purpose to defeat armor. This ammo type is restricted to the general public and is not easily acquired. The projectile consists of 3 materials: a soft metallic jacket and a two-part core. The core consists of a hardened material (the denser the better) like tungsten, steel, titanium, or depleted uranium and a lead layer between the penetrator and jacket suspending the penetrator concentrically for flight path stabilization.
EP - Enhanced Penetrator. These rounds are most often confused with AP-type rounds. The most common example of an EP round is the 5.56x45mm M855 “Green Tip” ammo type. These have a mild steel core (not hardened like AP) and were intended to be used for penetrating mild surfaces that would otherwise disrupt a bullet's flight path such as glass, car door panels, wood, and drywall. Due to the heavier weight that EP rounds displace, they often cannot get to the same velocity as their lead and copper counterparts (to cite an example, the M193 5.56) and therefore are not as effective as penetrating armor.
FPS - Feet Per Second. This is the measurement of speed when referring to ballistics. Across the ocean, it is MPS or Meters Per Second. Be aware of this metric conversion when calculating ballistics of non-U.S. calibers.
Ball - Ball refers to a lead core and jacketed projectile, otherwise known as an FMJ.
Bullet - A kinetic projectile, usually fired from a gun, while being propelled by an explosive charge. The term is derived from the french word boulle (boullet), which means "small ball".
Bonded - This refers to an electrical or chemical process that bonds the lead core to the jacket. Projectile separation can cause inconsistencies in effectiveness and this is a way of ensuring the two components of the bullet are retained.
Cartridge - This is the proper term for an assembled case, projectile, powder, and primer. In other words; ready to fire ammo.
Casing - Brass. This is considered the body of the cartridge. The casing contains the powder inside, the projectile at the top, and the primer at the rear. When a weapon is fired, the casing is ejected.
FMJ - Full Metal Jacket can also be called FMC, or Full Metallic Cartridge. This is simply referring to a non-leaded type projectile. Most FMJ’s have copper or brass jackets with a lead core.
Grains - This is an additional metric to measure the effectiveness of a projectile. It specifically refers to its weight. It is most commonly expressed as GR. A single grain is .065 gram or 1/7000 of a pound. For example, a 50 BMG projectile weighing 668GR weighs .095 a pound.
JHP - Jacketed Hollow Point. This is referring to an opening in the tip of the bullet. This is to allow the bullet to open up, dumping its energy into soft targets. This is why JHPs are much easier to stop when compared to FMJs in all armor types. This round type is generally considered for self-defense and is popular primarily in handguns.
JSP - Jacketed Soft Point. This projectile type has a small protrusion of lead with a jacket that is similar to the JHP. The protrusion of the lead tip allows better feeding, and when fired, the tip smashes into the jacket, causing an FMJ type round in principle to act like a JHP when striking tissue. This round is primarily used in hunting circles and is popular in rifles.
LRN - Lead Round Nose. This is a lead-cast bullet with a semi-circle nose cone shape. This shape aids in feeding semi-automatics. Although LRNs can be popular with ammunition reloaders, their discharge and subsequent fouling make them generally unsavory.
Powder - Gun Powder. This is the propellant every cartridge uses to propel a projectile down the barrel. Most modern cartridges use smokeless powder, however, older firearms used black powder.
Projectile - A high-speed object in travel. This is an all-encompassing term to cover an object in motion that strikes another object. Projectiles can refer to a bullet when fired, or shrapnel/fragmentation from an explosive.
Primer - This is the “ignition source” of a cartridge and is seated in the centric dimple impression on the bottom of a cartridge. When the primer is hit by a firing pin, chemical combustion happens that ignites the powder propellants.
RN - Round Nose. This again refers to the semicircular conical shape of a bullet point. This shape aids in a combination of feeding in semi-automatic weapons, aerodynamics when fired, and penetration when striking a target.
MSC - Mild Steel Core. This is a 3 composition type projectile typically consisting of a jacket, and a two-layer core. The jacket can be typical copper or brass, and the two-layer core is a concentrically placed mild steel rod through the core, held in place to the jacket by a layer of lead. This is the same round type as an EP described above
NATO - North American Treaty Organization. This is the world body of working countries contributing to a world force formed after WWII. Ineptitude aside, this organization has agreed to STAN-AG (standard agreement doctrine) which requires them to use a unified weapon/ammo type that complies with U.S. forces. Most frequently seen next in ammo designations as 7.62NATO (a specific 147GR FMJ loading of .308) and 9mm NATO (a 124GR FMJ on a +P loading). Keep in mind that U.S. Calibers like .223 and .308 when translated to metric become 5.56mm and 7.62mm.
SWC - Semi-Wad Cutter. This refers to a flat-base-nosed projectile with a slight taper to it. This round type was invented by pressing LRN bullets into their cases backward when loading them. The thought process at the time was that the flat face penetrated less and dumped more energy into the target. This evolved to a round type that was not just backward loaded, but slightly conical for flight stabilization. This was ultimately made obsolete by the JHP.
+P - Plus Parabellum or + Powder (or Plus Powder). This refers to an extra bit of powder added to a cartridge. Most +P rounds fire a few hundred feet per second faster than their non +P counterparts. Note: not all weapons can fire +P ammo.