| Term |
Definition |
| A1 |
Of or referring to a characteristic of the
M16A1 (for example, an A1 rear sight) |
| A2 |
Of or referring to a characteristic of the
M16A2 (for example, an A2 flash hider) |
| A3 |
Of or referring to a characteristic of the
M16A3, or (in civilian parlance) a flattop receiver. Note that the M16A3 is
essentially just a fullauto M16A2, but civilian manufacturers began using the
term A3 for flattop receivers before the military adopted the M16A3. |
| A4 |
Of or referring to a characteristic of the
M16A4 (for example, a flattop A4 upper receiver) |
| ACOG |
Advanced Combat Optical Gunsight
(Manufacturered by Trijicon and is issued to US military) |
| ACR |
Advanced Combat Rifle (a late 1980's weapon
development program intended to replace the M16 more detail here) |
| AD |
Accidental Discharge (a nonnegligent
unintentional discharge of a weapon that could not have been reasonably
forseen and prevented e.g. a caused by
an unexpected mechanical failure) |
| AF |
Air Force |
| AFG |
Angled Foregrip (trademarked name for a
unique MAGPUL foregrip) |
| AOW |
Any Other Weapon (any weapon capable of
discharging a shot that is not otherwise categorized under the NFA) |
| ARD |
AntiReflection Device (a device placed on
the objective of an optic to reduce reflections and glare) |
| AWB |
Assault Weapons Ban |
| BAC |
Bindon Aiming Concept (the idea behind
Trijicon optics like the ACOG that are designed to combine the rapid
acquisition of unmagnified sights with the accuracy of traditional magnified
scopes. Requires the use of both eyes in the manner of OEGs. website) |
| BBL |
Barrel |
| BC |
Ballistic Coefficient (a measure of a
bullet's ability to slip through the air unhindered by drag higher values indicate more streamlined
bullets) |
| B/C/CH |
Bolt, Carrier, Charging Handle (the assembly
of parts that cycles rounds into the chamber) |
| BCG |
Bolt Carrier Group (the bolt, bolt carrier,
gas key, cam pin, etc.) |
| BDC |
Bullet Drop Compensator (a mechanism in a
sight to compensate for a bullet's trajectory drop at long distances) |
| BFA |
Blank Firing Adapter |
| BHO |
Bolt Hold Open (a mechanism that holds the
bolt open when the magazine is empty, allowing for faster reloads) |
| BIY |
Build It Yourself |
| BL |
Bayonet Lug |
| BRASS |
BreatheRelaxAimSlackSqueeze (mnemonic for
steps of accurate shooting there are
many variants of this including BreathRelaxAimSightSqueeze and Breath |
| BRASSF |
BreatheRelaxAimStopSqueezeFollow Through
(mnemonic for steps of accurate shooting as taught by the USMC more detail here) |
| BRD |
Black Rifle Disease (a mysterious ailment in
which the sufferer develops an insatiable desire for more and more AR15s) |
| BSZ |
Battle Sight Zero |
| BT |
Boat Tail (a bullet that tapers at the back
like the tail of a boat rather than cuts off at a right angle see the Ammo Oracle) |
| BUIS |
Backup Iron Sight |
| BZO |
Battle Sight Zero |
| C3 |
Class 3 (a class of restricted weapons as
defined by the NFA, including machine guns, suppressors, shortbarreled
rifles, shortbarreled shotguns, etc.) |
| CAR |
Carbine |
| C.A.R. |
Colt Automatic Rifle |
| CCH |
Cut Carry Handle (a carry handle cut down to
form a BUIS) |
| CCO |
Close Combat Optic (an optic designed for
close range use, typically low power, parallax free and with long eye relief.
The Aimpoint M68 is an example.) |
| CH |
Carry Handle |
| CH |
Charging Handle |
| CIII |
Class 3 (a class of restricted weapons as
defined by the NFA, including machine guns, suppressors, shortbarreled
rifles, shortbarreled shotguns, etc.) |
| CLP |
Cleaner, Lubricant, Protectant (allpurpose
gun maintenance product example one,
example two, example three) |
| CMP |
Civilian Marksmanship Program (website) |
| COLL |
Collapsible (as in a collapsible stock) |
| CQB |
Close Quarters Battle |
| CQ/T (also
CQT) |
Close Quarters / Tactical (a 13x optic made
by Leupold and designed for close quarters battle with some midrange
capability as well) |
| CTR |
Compact/Type Restricted (an adjustable
carbine stock made by Magpul, with a friction lock feature) |
| DC |
Dust Cover |
| DCH |
Detachable Carry Handle |
| DCM |
Director of Civilian Marksmanship (replaced
by the CMP) |
| DD |
Destructive Device (an explosive,
incendiary, or poison gas device as defined by the NFA) |
| DEWAT |
Deactivated War Trophy (a machine gun whose
barrel has been plugged and welded to the receiver and whose chamber has been
welded shut, rendering it unserviceable but still subject to the regulations
of the NFA) |
| DI |
Direct Impingement (firearm operating system
where the action is cycled directly by the cartridge gasses. Most famously
used in the AR15 and M16 series of rifles. More information here and here.) |
| DIAS |
DropIn Auto Sear (a device used to convert a
semiautomatic gun to fullauto. By itself considered to be a machine gun under
the NFA, and unregistered ones are illegal to even possess with, let alone
install in, the guns they convert) |
| DIY |
Do It Yourself |
| DOD |
Department Of Defense |
| EBR |
Evil Black Rifle (a twist on the
gungrabbers' propaganda, embraced by supporters of the RKBA to both
endearingly and sarcastically refer to militarystyle rifles such as the AR15) |
| FA |
Forward Assist |
| FA |
Full Auto |
| FAR |
Featherweight Assault Rifle |
| FCG |
Fire Control Group (the hammer, trigger,
disconnector, springs and selector) |
| FDE |
Flat Dark Earth (a tanbrown color making
inroads as a replacement for black in weapon coloring) |
| FF |
Free Float/Floated/Floating |
| FFL |
Federal Firearms License/Licensee (a license
that permits one to sell & transfer guns in interstate commerce, or the
holder of that license) |
| FH |
Flash Hider |
| FIRSH |
Free Floating Integral Rail System Handguard
(see Olympic Arm's website) |
| FMJ |
Full Metal Jacket (a bullet that is fully
encased in a metal jacket see the Ammo
Oracle) |
| FMJBT |
Full Metal Jacket Boat Tail (a FMJ BT
bullet see the Ammo Oracle) |
| FP |
Firing Pin |
| FS |
Flash Suppressor |
| FSB |
Front Sight Base |
| FSP |
Front Sight Post |
| FST |
Front Sight Tower |
| FTE |
Fail To Eject/Extract (please substitute the
more precise FTEj or FTEx as appropriate to make clear your intention) |
| FTEj |
Fail To Eject |
| FTEx |
Fail To Extract |
| FTF |
Fail To Feed (if used without an unambiguous
context, this acronym may be confused with "Fail To Fire" as listed
below) |
| FTF |
Fail To Fire (if used without an unambiguous
context, this acronym may be confused with "Fail To Feed" as listed
above) |
| FUBAR |
Fouled Up Beyond All Recognition (substitute
more colorful adjective for "Fouled" as desired) |
| GCA |
Gun Control Act of 1968 (The law that, among
other things, established the FFL license system, set a minimum age to
purchase guns, and banned the import of "nonsporting" guns,
eventually including militarystyle guns) |
| HBAR |
Heavy Barrel |
| HG |
Handguard |
| HP |
Hollow Point (a bullet with a hollow cavity
at the tip) |
| HSLD |
High Speed, Low Drag (of or relating to
special forces and other highly skilled operators) |
| HTS |
Hammer, Trigger, Sear (parts of the FCG) |
| IAD |
Immediate Action Drill (a sequence of
actions performed in response to a situation requiring immediate and
instinctive resolution in this context
a weapon malfunction) |
| IBZ |
Improved Battlesight Zero (All purpose zero
invented by Lt. Colonel Chuck Santose. Set at 50 yards, it gives a very flat
trajectory out to 250 meters. Instructions here.) |
| ID |
Inside Diameter |
| ID |
Involuntary Discharge (an unintentional
discharge of a weapon resulting from a physical reaction beyond the shooter's
instant control e.g. a muscle spasm) |
| IPSC |
International Practical Shooting
Confederation (organizes and sponsors shooting competitions emphasizing a
combination of accuracy, power, and speed
website) |
| JHP |
Jacketed Hollow Point (a bullet that is
jacketed in metal, but with a hollow cavity at the tip see the Ammo Oracle) |
| JSP |
Jacketed Soft Point (a bullet that is
jacketed in metal, but with exposed lead at the tip see the Ammo Oracle) |
| KB |
KaBoom (explosive failure of a firearm caused by problems such as outofbattery
firing, bore obstructions, etc.) |
| KBC |
Keyboard Commando (a person who buys and
opines on expensive tactical gear but who has no actual combat or law
enforcement training or experience) |
| KISS |
Keep It Simple, Stupid (an admonition to
avoid complexity with its attendant expense and unreliability, also used as
an adjective to describe something that adheres to the KISS philosophy) |
| LC |
Lake City (a federally owned, contractor
operated plant in Missouri where small arms ammunition is made for the U.S.
military) |
| LE |
Law Enforcement |
| LEO |
Law Enforcement Officer |
| LEO |
Law Enforcement Only (an item that can
legally be used only by law enforcement agencies and their personnel) |
| LL |
Lightning Link (a device for converting a
semiautomatic gun to fullauto. By itself considered to be a machine gun under
the NFA, and unregistered ones are illegal to even possess with, let alone
install in, the guns they convert) |
| LOP |
Length Of Pull (the distance from the face
of the trigger to the end of the buttstock) |
| LPK |
Lower Parts Kit |
| LRC |
Living Room Commando (a person who buys and
opines on expensive tactical gear but who has no actual combat or law
enforcement training or experience) |
| LULA |
Loader/Unloader Accessory (for fast loading
and unloading of magazines website) |
| LW |
Lightweight |
| M16 |
The original fullauto military version of
the AR15 rifle (includes triangular crosssection handguards, early style rear
sight that is not adjustable for range, and a 1:12 twist barrel: photos) |
| M16A1 |
Later variant of the M16 that added a
forward assist to jam the bolt home when the normal action cycling doesn't:
photos) |
| M16A2 |
Later variant of the M16A1 that switched to
a rangeadjustable rear sight, a 1:7 twist barrel, round crosssection
handguards and substituted a threeround burst firing mode for the fullauto
mode: photos) |
| M16A3 |
Later variant of the M16A2 that substitutes
fullauto firing for the threeround burst mode of the M16A2. Initially adopted
by the Navy SEALS: photos) |
| M16A4 |
Later variant of the M16A2 that added a
flattop upper receiver with removable carry handle but maintained the
threeround burst firing mode: photos) |
| M193 |
55 grain FMJBT military cartridge, usable in
1:14 to 1:7 twist barrels (see the Ammo Oracle) |
| M4 |
A 14.5" barrel carbine version of the
M16A2. Earlier models have an integral A2 carry handle, later ones have a
flattop upper (photos) |
| M4A1 |
A variant of the M4 that includes fullauto
fire and a flattop upper with removable carry handle (photos) |
| M4GERY |
A rifle designed to mimic the appearance and
function of a true M4, but that isn't an official military M4 (pronounced
"em forgery") |
| M855 |
62 grain FMJBT military cartridge, usable in
1:10 to 1:7 twist barrels (see the Ammo Oracle) |
| MARPAT |
MARine PATtern (a digital camouflage
pattern. Examples here, controversy here and here.) |
| MARS |
Multipurpose Aiming Reflex Sight (an Israeli
sight that combines a reflex reddot sight with a laser (visible or IR) aiming
light website) |
| MIAD |
MIssion ADaptable (a modular grip
manufactured by Magpul website) |
| MOA |
Minute Of Angle (a measure of angular
displacement equal to 1/60 of one degree, usually used when discussing group
sizes 1 MOA is roughly 1" at 100
yds) |
| MOUT |
Military Operations on Urbanized Terrain |
| M&P |
Military and Police (A trademark of Swith
and Wesson for a line of pistols and AR15 rifles) |
| MP |
Magnetic Particle [inspection/testing]
Magnetic particle inspection is a nondestructive steel inspection method used
to ensure that a barrel, for example, is free from metallurgical defects such
as cracks. |
| MRE |
More Real Estate (a rail adapter system that
extends past the FSB, made by KAC) |
| MRE |
Meal Ready to Eat. The food provision for
the US Military. |
| MRF |
Modular Rail Forend (a rail adapter system
made by Troy Industries) |
| MRP |
Monolithic Rail Platform (an integrated AR15
upper receiver and rail adapter system, made by LMT) |
| MSRP |
Manufacturer's Suggested Retail Price |
| MRS |
Modular Rail System (LeitnerWise's
lightweight, quickchange barrel system designed for use with standard AR15
lowers) |
| MR/T (also
MRT) |
Mid Range / Tactical (a line of optics made
by Leupold and designed for midrange capability) |
| MWS |
Modular Weapon System |
| ND |
Negligent Discharge (an unintentional
discharge of a weapon that reasonably should have been foreseen and
prevented) |
| NFA |
National Firearms Act (of 1934 the law governing machine guns, sawed off
shotguns, short barreled weapons, suppressors, etc.) |
| NICS |
National Instant Criminal Background Check
System (the system established as part of the Brady Act to check for
disqualifying information that would prevent legal transfer of a firearm to a
person) |
| NM |
National Match (a competition sponsored by
the CMP) |
| NOD |
Night Observation Device |
| NOS |
New Old Stock (generally used in connection
with an item that can no longer be manufactured new, but that can be sold
from existing stock: an item that is chronologically old, but that has been
sitting in storage and was never sold at retail or used before) |
| NRA |
National Rifle Association (website) |
| NSN |
National Stock Number (a unique number
assigned to each item in the Federal Supply Cataloging System, including
parts and accessories for military weapons such as the M16) |
| NSW |
Naval Special Warfare |
| NTCH |
Nose To Charging Handle (a cheek weld
[placement of the side of one's face against the stock] where the tip of the
nose touches the charging handle, thus giving a consistent position and sight
picture) |
| NVD |
Night Vision Device |
| OAL |
Overall Length |
| OBI |
Open Bolt Indicator a flag inserted into a firearm receiver to
show that the bolt is open (and thus in a safe condition) |
| OD |
Olive Drab (that green color the army is so
fond of) |
| OD |
Outside Diameter |
| OEG |
Occluded Eye Gunsight (a sight that projects
a dot to the eye but through which you can't actually see the target hence the term "occluded". It
works via binocular vision whereby one eye views the target directly, the
other eye views the dot in the sight, and your brain merges the two images
together) |
| OICW |
Objective Individual Combat Weapon (possible
M16 replacement weapon system that can fire both normal bullets and airburst
fragmenting munitions. The XM8 is based on the normal bullet firing component
an early OICW entry. Overview) |
| OTM |
Open Tip Match (a type of hollow point
bullet designed for long range accuracy) |
| OPS |
Operations (see also OPSINC just below) |
| OTAL |
Offset Tactical Aiming Laser (a laser sight
mounted alongside the barrel/handguards/carry handle) |
| PAFS |
Permanently Attached Flash Suppressor
(generally permanently attached in order to bring a barrel's overall length
to 16" and thus avoid the legal restrictions on SBRs) |
| PD |
Police Department |
| PDW |
Personal Defense Weapon (a generally compact
weapon designed primarily for defensive rather than offensive operations, for
example the FN P90) |
| PM |
Preventative Maintenance |
| POA |
Point Of Aim |
| POI |
Point Of Impact |
| PRK |
People's Republic of Kalifornia (a name for
California that alludes to the state's rather draconian, some would say
Communistlike, antigun laws) |
| PRNJ |
People's Republic of New Jersey (see PRK) |
| PRNY |
People's Republic of New York (see PRK) |
| PRS |
Precision Rifle/Sniper (a precision stock
made by Magpul, adjustable for height and LOP) |
| PSD |
Personal Security Detail/Detachment (a group
of security specialists who travel with and provide personal protection for a
highranking or valuable person) |
| Q3131A |
M193 ammunition packaged for sale to
civilians (may fail to meet some aspect of military standard see the Ammo Oracle) |
| QCB |
Quick Change Barrel |
| QD |
Quick Detach |
| RAS |
Rail Adapter System |
| RDIAS |
Registered DropIn Auto Sear (a DIAS legally
registered under the NFA. By itself considered to be a machine gun under the
NFA) |
| RECCE |
Reconnaissance (in this context a 16"
free floating match barrel upper, ACOG optic, originally used by SEALS) |
| RIS |
Rail Interface System |
| RKBA |
Right to Keep and Bear Arms |
| RLL |
Registered Lightning Link (a LL legally
registered under the NFA. By itself considered to be a machine gun under the
NFA) |
| ROF |
Rate Of Fire |
| RR |
Registered Receiver (a receiver, typically
for a machine gun, registered under the NFA) |
| SAAMI |
Sporting Arms and Ammunition Manufacturers'
Institute (an association of manufacturers of sporting firearms, ammunition,
and components. Often used to distinguish between the sporting .223 chamber
[the SAAMI chamber] and the military 5.56 mm chamber ) |
| SAMR |
Squad Advanced
Marksman Rifle (20" match barrel upper with Leupold scope, used by the
Marines more info) |
| SAR |
Small Arms Review (website) |
| SAW |
Squad Automatic Weapon |
| SBR |
ShortBarreled Rifle (a rifle whose barrel is
less than 16" long as defined by the NFA) |
| SCAR |
Special Operations Forces Combat Assault
Rifle (additional information here) |
| SD |
Shell Deflector |
| SDMR |
Squad Designated
Marksman Rifle (20" match barrel upper with ACOG scope, used by the
Army more info) |
| SEBR |
Special Edition Black Rifle (a custom AR15
rifle sold as part of a group buy run by AR15.com) |
| SF |
Special Forces |
| SGN |
Shotgun News (a venerable gun sales
publication made up entirely of display and classified advertising, first
published in 1946 website) |
| SIR |
Selective Integrated Rail (see A.R.M.S.
website) |
| SMG |
Sub Machine Gun |
| SMK |
Sierra Match King (a hollow tip bullet
designed for long range accuracy, made by Sierra Bullets website) |
| SOCOM |
Special Operations Command |
| SOPMOD |
Special Operations Peculiar Modification |
| SOF |
Special Operations Forces (in addition to
its standard military usage, also a designation for a now discontinued
midlength AR15 carbine made by ArmaLite) |
| SOT |
Special Occupational Taxpayer (a person
whose occupation [e.g. manufacturer/importer/dealer of NFA weapons] exempts
him from paying NFA transfer taxes) |
| SP |
Soft Point (a bullet whose lead tip is
exposed rather than jacketed in a harder metal) |
| SPC |
Special Purpose Cartridge (as in the new 6.8
mm SPC) |
| SPORTS |
Mnemonic for AR15 immediate action drill:
Slap the bottom of the magazine. Pull the charging handle. Observe the open
chamber area. Release the charging handle. Tap the forward assist. Shoot.
Some people consider this to be remedial action rather than immediate action.
See also TRB and TPRRRS. |
| SPR |
Special Purpose Rifle (18" free
floating match barrel upper) |
| SS |
Stainless Steel |
| SUM |
Stainless Ultra Match (Olympic Arms' name
for their stainless steel barrel made with broachcut rifling for
accuracy website) |
| T |
Top (as in the numbered stations on the top
rail of an A4 upper) |
| TCH |
Tactical Carry Handle (a specialized carry
handle made by RRA and designed to mount Aimpoint red dot sights via
Aimpoint's low ring website) |
| TDP |
Technical Data Package (the collection of
drawings, engineering notes, etc. that describe in detail the design and
construction of an item) |
| T&E |
Test and Evaluation |
| TEOTWAWKI |
The End Of The World As We Know It |
| TM |
Technical Manual |
| TPRRRS |
Tap, Pull, Rack, Roll, Release, Shoot (an
alternative to the traditional SPORTS IAD, described here) |
| TRB |
Tap Rack Bang (an immediate action drill:
tap the bottom of the magazine to ensure it is seated, rack the slide, and
shoot [bang]. See also SPORTS and TPRRRS) |
| UBR |
Utility/Battle Rifle (a general purpose
adjustable stock made by Magpul, with a fixed cheekweld. Successor to the
M93B.) |
| UD |
Unintentional Discharge (a weapon discharge
made without deliberate or conscious intent, including accidental,
involuntary and negligent discharges) |
| URX |
Upper Receiver eXtension (a freefloating
rail system made by Knight's Armament) |
| USGI |
United States Government Issue (often in
reference to magazines most regard
USGI mags as the best) |
| USMC |
United States Marine Corps |
| VFG |
Vertical Fore/Forward/Front Grip |
| WSSM |
Winchester Super Short Magnum |
| WWB |
Winchester White Box (In AR15 context,
Q3131A ammunition made in Israel to M193 specifications relatively inexpensive but reliable general
purpose ammo) |
| XCR |
eXchangeable Caliber Rifle* (Robinson
Armament's modular battle rifle, originally intended as a SCAR contender) |
| XM193 |
M193 ammunition packaged for sale to
civilians (may fail to meet some aspect of military standard see the Ammo Oracle) |
| XM8 |
Designation of a modular weapon system that
may replace the M16 family of rifles. Adoption of the XM8 is uncertain.
(brochure, overview) |
| Z |
Zero (marked on some A2style rear sight
elevation knobs to indicate the position at which the knob should be set when
establishing a battlesight zero on a 25meter range according to standard
military doctrine) |
| ZM |
ZMan or ZittaMan {Weapons} (manufacturer of
the LR300 oprod gas system upper/rifle and LR300/AR15 accessories website) |
