0-9

• 1911: A classic semi-automatic pistol design created by John Moses Browning. It is famous for its steel frame, grip safety, and crisp trigger.
• 40mm NATO Thread: A universal sizing standard for gas masks. It guarantees that any filter with this screw pattern will perfectly fit and seal onto your mask.
• 4-Pin / 5-Pin / 6-Pin / 10-Pin: These describe the number of metal contact points inside a radio or headset connector used to pass power and sound.
• 7075 Aluminum: A high-strength aluminum alloy often used for rifle receivers and handguards. It is nearly as strong as some steels but much lighter.
• .300 Blackout: A rifle cartridge designed to work in standard AR-15s but with a heavier bullet. It is famous for being extremely quiet when used with a suppressor.
• .50 BMG: A massive cartridge originally made for machine guns. Today, it is used in long-range sniper rifles to hit targets over a mile away or disable vehicles.
• 5.56mm NATO: The standard military rifle round for the U.S. and its allies. It is fast, light, and almost identical to the civilian .223 Remington.

A

• Accessory Rail: The jagged metal strip on a gun or helmet where you attach items like lights, lasers, and grips.
• Action Type: The mechanical system that loads, fires, and ejects a shell. Common types are bolt-action (manual) and semi-automatic (self-loading).
• Airsoft: Training guns that look like real firearms but shoot plastic balls using compressed gas or springs. They are used for training because they don't cause serious injury.
• ALICE: An "old school" gear system used by the military before MOLLE. It uses metal clips to attach pouches instead of nylon weaving.
• Ambidextrous (Ambi): Controls like safety levers or magazine releases that can be used by both right-handed and left-handed shooters.
• Amphenol: A brand of rugged connectors used in high-end military radios. Think of it like a "USB port" built to survive mud, rain, and rough handling.
• ANVIS (Aviator Night Vision Imaging System): A style of night vision goggles originally designed for pilots, typically featuring a specialized mount and a focus on high clarity.
• Anti-Materiel Rifle: A heavy-duty rifle (usually .50 caliber) designed to destroy hard targets like radar dishes or engine blocks rather than just troops.
• Apparent Field of View: How wide the image looks to your eye when looking through a scope. A wider view helps you see more area without turning your head.
• AR-15: The civilian version of the military M16/M4. It is semi-automatic and the most popular rifle platform in America due to its modularity.
• AR Pistol: A firearm based on the AR-15 that has a barrel shorter than 16 inches and no stock. It is legally classified as a pistol.
• Aramid (Kevlar): A family of super-strong, heat-resistant threads. Woven together like a tight net, these fibers catch handgun bullets and spread the impact out.
• Armorer: A certified technician trained to fully take apart, repair, and build firearms.
• Assault Pack: A medium-sized backpack (usually 20 to 40 liters) designed to hold enough gear for a 1-to-3 day mission.
• Assault Rifle: Technically, a military rifle that can switch between semi-automatic and fully automatic fire.
• ATM (Atmospheres): A rating for water resistance. ATM 10 means the device can withstand water pressure at a depth of 100 meters (about 330 feet).
• Autogating: A safety feature for Night Vision Goggles. It rapidly turns the power on and off to protect the image tube from getting damaged by bright flashes of light.

B

• Backface Deformation (BFD): A measurement of how deep body armor bulges inward against your body when it stops a bullet. Less bulge means less blunt force trauma.
• Baffle: Cone-shaped metal cups inside a suppressor. They trap and slow down expanding gas to reduce the noise of a gunshot.
• Ballistic Data Exchange (BDX): A smart technology where your rangefinder talks to your scope via Bluetooth to automatically adjust your aiming point for distance.
• Battle Belt: A padded belt covered in MOLLE webbing. It allows you to carry your pistol and ammo on your hips, taking weight off your shoulders.
• Bayonet Lock: A type of connector plug that you push in and twist to lock. It prevents cables from being ripped out during movement.
• Bolt Carrier Group (BCG): The mechanical heart of an AR-15. It moves back and forth with every shot to eject the empty shell and load a new one.
• Bolt Action: A simple rifle system where you manually lift and pull a handle to load the next bullet. Common on sniper rifles for maximum accuracy.
• Bore: The inside of the barrel where the bullet travels.
• Buffer Tube: The metal tube sticking out the back of an AR-15. It houses a spring that absorbs the "kick" or recoil of the gun.
• Bullpup: A rifle design where the magazine and action are located behind the trigger. This allows the gun to be short and compact while keeping a full-length barrel.
• Bump Helmet: A tactical helmet that stops impacts (like hitting your head on a doorframe), not bullets. It is much lighter and cheaper than a ballistic helmet.

C

• Caliber: The diameter (width) of the bullet. Common examples are 9mm or 5.56mm.
• Candela: Measures how far a light beam can reach. High candela means a tight, focused beam (spotlight). Low candela means a wide, flooding light.
• Ceramic Armor: Hard armor plates made from advanced ceramics. They are lighter than steel and excellent at stopping armor-piercing rounds, but can crack if dropped hard.
• Cerakote: A ceramic-based paint baked onto firearms. It is much tougher than regular paint and protects against rust and scratches.
• Charging Handle: The lever you pull to manually load the first bullet into the chamber of a semi-automatic rifle.
• Chest Rig: A lightweight gear carrier that straps over your shoulders to hold magazines on your chest. Unlike a plate carrier, it does not hold armor.
• Cold Hammer Forged (CHF): A way of making barrels by pounding the steel around a form. These barrels are denser and last much longer than standard ones.
• Compensator: A muzzle device that vents gas upward. This pushes the barrel down when you fire, helping you stay on target for the next shot.
• Co-Witness: When you can look through your red dot sight and still see your iron sights aligned in the bottom of the window as a backup.

D

• Decibel (dB): A unit for measuring sound. A gunshot is around 140 dB (instant damage); hearing protection brings this down to safe levels.
• Denier (D): A measurement of fabric thickness. 500D is standard for plate carriers (strong but light), while 1000D is heavy-duty and stiff.
• Direct Impingement (DI): The gas system used in most AR-15s. It blows gas directly back into the bolt to cycle the gun.
• Diverging Image Tube (DIT): A night vision design where the tubes point slightly outward. This stretches your vision wider, allowing you to see more out of the corner of your eye.
• Dovetail Mount: A common type of mounting system for sights where a wedge-shaped piece fits into a matching slot, often found on handgun slides.
• Dual Comm: A headset setup that lets you talk on two different radio channels (like squad and headquarters) at the same time.

E

• EBI (Equivalent Background Illumination): Measures the "phantom light" a night vision tube creates when it is pitch black. A lower number is better for seeing in total darkness.
• EDC (Everyday Carry): The gear you carry on you every single day to be prepared, usually including a pistol, knife, light, and tourniquet.
• eVent: A material similar to Gore-Tex that uses a "dry system" to let sweat out immediately without needing the fabric to get damp first.
• Eye Relief: The distance your eye must be from a scope to see the full picture. If you are too close, the scope might hit your eye during recoil ("scope bite").

F

• FAST Helmet: A modern combat helmet with a "high-cut" design that leaves your ears exposed for large radio headsets.
• Figure of Merit (FOM): The "horsepower" rating of a night vision tube. A higher FOM means a better, clearer image.
• Fire Control Group (FCG): The internal parts of a gun that make it fire, including the trigger, hammer, and sear.
• First Focal Plane (FFP): A type of scope where the crosshair grows or shrinks as you zoom. This keeps the measurement marks accurate at any magnification.
• Flash Hider: A device on the barrel that disperses burning gas so you don't see a giant fireball when shooting at night.
• Footprint: The specific mounting pattern on a handgun slide (e.g., RMR footprint) that determines which red dot optics will fit.
• Free-Floating Barrel: A barrel that does not touch the handguard. This improves accuracy because resting the gun on a barrier won't warp the barrel's alignment.

G

• Gas / Vapor Filter: A chemical filter packed with treated charcoal. It traps poisonous gas molecules so only clean air reaches your lungs.
• Germanium: A rare metal used to make the lenses for thermal optics. Unlike glass, germanium allows heat (infrared energy) to pass through so the sensor can "see" it.
• Gore-Tex: A waterproof, breathable fabric membrane. It keeps rain and wind out while allowing sweat vapor to escape, keeping you dry during movement.
• Grains (gr.): A unit of weight used to measure the mass of a projectile (the bullet itself). Heavier bullets generally carry more energy but travel slower than lighter ones of the same caliber.
• Green Phosphor (GP): The classic "green glow" seen in standard night vision.
• Green Tip (M855): 5.56mm military ammo with a steel "penetrator" tip designed to punch through light barriers like car doors.

H

• HALO: Measures the size of the "glare" circle around bright lights in night vision. A smaller Halo value is better.
• Headspace: The precise distance between the bolt face and the barrel chamber. If this is off, the gun can be dangerous to fire.
• Hollow Point: A bullet with a hollow tip designed to expand (mushroom) when it hits a target. This creates a larger wound and prevents the bullet from passing through walls.

I

• IFAK (Individual First Aid Kit): A compact medical pouch containing life-saving trauma gear like tourniquets and chest seals.
• Image Intensifier Tube (I2): The heart of a night vision device. It takes a tiny amount of light and multiplies it thousands of times into an image.
• Infrared (IR): Light that is invisible to the naked eye but acts like a spotlight for night vision goggles.
• IP Ratings (Ingress Protection): A standard for how well a device is protected from dust and water.
• IP67: Totally dust-proof and can be dropped into water up to 1 meter deep for 30 minutes.
• IP68: Totally dust-proof and can be submerged in deeper water (usually 1.5 meters or more) for longer periods.

L

• LEMO: A high-end, push-pull connector used for power cables on night vision. It is waterproof and very secure.
• Level IIIA+: A special rating showing armor exceeds normal tests, often stopping shotgun slugs or high-velocity pistol rounds.
• Level IV: The highest rating for hard armor plates. It is tested to stop armor-piercing rifle rounds.
• Liner Systems: The internal padding and adjustment systems (like dial liners) inside a helmet that provide comfort and impact protection.
• Lumens: Measures the total light output of a flashlight. Think of this as the "raw power" of the light.
• LWIR (Long Wave Infrared): The heat energy detected by most tactical thermal scopes to see bodies or engines in total darkness.

M

• M-LOK: The modern standard for attaching accessories to a rifle handguard using slots rather than bulky rails.
• Match Grade: Parts made to extremely tight tolerances for competition. Match ammo is more consistent and accurate than bulk ammo.
• Merino Wool: A natural fiber from Merino sheep. Unlike regular wool, it is extremely soft and non-itchy. It naturally regulates temperature, wicks moisture away, and resists odors, making it ideal for tactical base layers and socks.
• Minute of Angle (MOA): A unit for measuring aim. 1 MOA is roughly 1 inch at 100 yards.
• MOLLE: The standard system of nylon loops on tactical vests that lets you weave pouches onto your gear so they never fall off.
• MRAD (Milliradian): The metric version of MOA, preferred by military snipers. 0.1 MRAD moves the bullet impact 1 cm at 100 meters.
• MRE (Meal, Ready-to-Eat): A self-contained, individual field ration in lightweight packaging used by the military.
• Muzzle Brake: A device that redirects gas sideways to reduce recoil. It makes the gun louder for people standing next to you.

N

• NATO Wiring: The standard wiring setup for military headsets. It ensures your headset works with standard PTT (Push-to-Talk) buttons.
• NeoShell: A highly breathable and stretchy waterproof material often used in tactical clothing for high-activity missions.
• NETD: A score for thermal sensors. A lower number (like <35mK) means a sharper heat image.
• NiB (Nickel Boron): A high-performance coating used on gun parts (like the bolt). It is extremely slick, reduces friction, and can be cleaned easily even without oil.
• NIJ 0101.07 Standard: The newest system for testing body armor, using "HG" for Handgun and "RF" for Rifle protection tiers.
• NIR (Near Infrared): The light spectrum just beyond visible red that night vision goggles use to "see" in the dark.

O

• Offset Sights: Sights mounted at a 45-degree angle. You tilt the rifle sideways to use them for close-range shots when your main scope is zoomed in.
• Open Tip Match (OTM): Precision bullets with a tiny opening at the tip, designed for flight stability and extreme accuracy.

P

• Particulate Filter: A filter that acts like a microscopic net to catch dust, smoke, and viruses. It cannot stop invisible chemical gases.
• PEAD (Polyethylene): A military-grade plastic stronger than steel but light enough to float. Used for lightweight helmets and armor plates.
• Photocathode Sensitivity: A measurement of how well night vision goggles turn starlight into electricity. Higher numbers mean a brighter, clearer picture.
• Photonic Barrier: A technique where you shine an extremely bright, high-candela light at a threat. It creates a "wall of light" that blinds the opponent and hides your location.
• Picatinny Rail: The classic "cheese grater" rail system. It is heavy but very secure for mounting optics.
• Pistol Caliber Carbine (PCC): A rifle that shoots handgun ammo (like 9mm). They are cheaper to shoot and have less recoil than full-power rifles.
• Plate Carrier: A tactical vest designed to hold hard armor plates over your heart and lungs.
• Push-to-Talk (PTT): The button on your vest that you hold down to speak on the radio.
• PVS Style: Refers to the standard military naming convention for night vision devices (like the PVS-14 monocular).

Q

• Quicklace: A system of high-strength laces and a sliding cam-lock that allows you to tighten boots perfectly with one pull.

R

• Rangefinder: A laser device that tells you the exact distance to your target.
• Red Dot Sight (RDS): An electronic optic that provides a simple red dot as an aiming point.
• Resolution (Night Vision): A measurement of how crisp and sharp the night vision picture is.
• Reticle: The crosshair or aiming point inside a scope or red dot.
• RMR (Ruggedized Miniature Reflex): A very popular red dot sight footprint used for handguns.
• Rucksack: A large, heavy-duty backpack meant for long missions lasting several days.

S

• SAPI Plates: The standard "Small Arms Protective Insert" shape for military armor plates.
• Shelf Life (CBRN): The amount of time a gas mask filter can sit in storage before the chemicals inside stop working (usually 10-20 years).
• Signal-to-Noise Ratio (SNR): Measures the clarity of a night vision image. High SNR means a clear image; low SNR means "static" or "snow".
• Silencer Threads (Thread Pitch): The measurement of the screw grooves on a barrel muzzle (e.g., $1/2 \times 28$). Your suppressor must match this exactly to fit.
• Single Comm: A headset designed to connect to only one radio.
• Spalling: When a bullet hits a steel plate and shatters into tiny fragments. "Spall coating" is a rubber layer that catches these fragments.
• Stabproof: Armor designed to stop sharp objects like knives or needles. Standard bulletproof vests often do not stop blades.
• Striker Fired: A pistol with no external hammer (like a Glock). An internal spring-loaded pin hits the primer.
• Subsonic Ammo: Ammunition that flies slower than the speed of sound. It does not make a loud "crack" (sonic boom), making it very quiet with a suppressor.
• Suppressor (Silencer): A cylinder attached to the barrel that traps gas to lower the sound. It protects hearing but is not "silent".

T

• Thermal: Optics that see heat, not light. They can spot people hiding in bushes because body heat stands out against the cold.
• Tourniquet (TQ): A device used to stop massive bleeding by tightening around a limb. It is the #1 life-saving tool in a gunfight.
• Trauma Pad: A soft foam pad worn behind hard armor to reduce bruising and broken ribs from a bullet impact.
• Tritium: A radioactive material that glows in the dark without batteries, used in handgun sights for low-light aiming.
• Twist Rate: How fast the spiraled grooves in a barrel spin the bullet. Heavier bullets need faster spins to stay stable.

U

• UHMWPE: A type of plastic spun into fibers. Lighter than steel and stronger than Kevlar.
• Upper / Lower Receiver: The two halves of an AR-15. The Upper holds the barrel and bolt; the Lower holds the trigger and magazine.

V

• V50 Ballistic Limit: A test where scientists find the exact speed a bullet must travel to have a 50/50 chance of punching through the armor.
• Viewport: The clear, bulletproof window in a tactical shield that lets you see safely while staying hidden.

W

• White Phosphor (WP): Modern night vision that displays the image in black and white (or light blue) instead of green.
• Witness Holes: Small holes in a magazine that let you see how many bullets are left.

Z

• Zeroing: The process of aligning your sights so the bullet hits exactly where the crosshair is pointing at a specific distance.
• Zero Stop: A mechanical lock on a scope that lets you instantly spin the dial back to your original starting point.