Legal Concepts & the AR15

Legal Concepts & the AR15

The right to keep and bear arms shall not be infringed, except that it is far too often.

The legality of owning an AR15 is complex and varies from place to place. That is why it is imperative that you know and understand the laws of your areas, and the areas in which you travel. Generally speaking, these types of infringements are known as, “Assault Weapon Bans” and are often purely cosmetic feel good type legislation.

For example standard pistol grips are often banned in some localities. Therefore products like the Monsterman grip were born. Often times vertical foregrips may be banned. Sometimes barrel shrouds are banned. Perhaps a detachable magazine is banned, therefore the bullet button was born. In some municipalities fixed butt stocks are banned and in others flash hiders or muzzle compensators are banned.

The over all length of the AR15 rifle or AR15 pistol is important.  The barrel length is important as well, since a barrel less than 16″ may cause the rifle to become a Short Barrel Rifle (SBR).

None of these features make the AR15 any more or less dangerous. But they are the rules and as law abiding gun owners we must abide by the rules, WHILE we work to fix the flawed laws.

History of the AR15 and predecessors

History of the AR15 and predecessors.

History of the AR15 and predecessors.

The AR 15, called by some “Lego’s for Adults”, is one of the most popular carbine rifles ever. The AR 15 was built on the M16 military platform and first introduced during the Vietnam police action. Part of the popularity for the AR15 rifle is its’ versatility and unique ability to be customized. Simply by changing an AR 15 upper assembly, you can completely change the rifle from a close quarters weapon to a long range tool. Therefore you can have multiple gun configurations without owning multiple guns.

Due to the popularity and flexibility of the rifle, there are also more upgrade parts available for the AR 15 than any other rifle on the market today.

Originally designed by Eugene Stoner for ArmaLite.

AR15 Definitions, Acronyms, and Abbreviations

AR15 Definitions, Acronyms, and Abbreviations


A1, A2, A3 etc… Refers to military designations or alterations of various firearms including M16 & M4.

AR – Means ArmaLite right?  There is some debate as to the meaning of AR as the original ArmaLite company designed the AR15 rifle, Colt later has a CAR 15, which was based on the original Eugene Stoner ArmaLite design, however the CAR meant Colt Automatic Rifle.

AWB – Assault Weapons Ban. An infringement on your 2nd Amendment rights is the classifying of what an assault weapon is typically by legislative body (government).

BBL – Barrel.

BCG – Bolt Carrier Group

BDC – Bullet Drop Compensator

BRD – Black Rifle Disease

BUIS – Back Up Iron Sight

CAR – Carbine. A carbine is a medium barrel length rifle, typically with a 16″ long barrel.

Compliant – Typically refers to Ar15′s or parts and accessories which adhere to various infringements, bans or restrictions; such as “California Compliant”.

CQB – Close Quarters Battle.

DC – Dust Cover

DCH – Detachable Carry Handle

DD – Daniel Defense

DD – Destructive Device

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.

DIAS – Drop-In Auto Sear

DIY – Do It Yourself

DPMS – Defense Procurement Manufacturing Services – builder of AR-15 rifles and supplier of parts and accessories

DSA – D.S. Arms

EBR – Evil Black Rifle

ETA – Estimated Time of Arrival

FA – Forward Assist

FA – Full Auto

FAQ – Frequently Asked Questions

FCG – Fire Control Group (the hammer, trigger, disconect, springs and selector)

FDE – Flat Dark Earth (a tan-brown 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 and/or  transfer guns in interstate commerce.

FH – Flash Hider

FMJ – Full Metal Jacket – a bullet that is encased in a metal jacket.

FMJBT – Full Metal Jacket Boat Tail

FN – Fabrique Nationale

FOIA – Freedom Of Information Act

FP – Firing Pin

FS – Flash Suppressor

FSB – Front Sight Base

FSP – Front Sight Post

FST – Front Sight Tower

FTE – Fail To Eject/Extract

FTEj – Fail To Eject

FTEx – Fail To Extract

FTF – Fail To Feed

LPK – Lower Parts Kits

FSB – Front Sight Base, sometimes called Front Sight Post.

GCA – Gun Control Act of 1968

HBAR – Heavy Barrel

HG – Handguard

HP – Hollow Point (a bullet with a hollow cavity at the tip)

HTS – Hammer, Trigger, Sear (parts of the FCG)

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 (Also See USPSA)

JHP – Jacketed Hollow Point – a bullet that is jacketed in metal, but with a hollow cavity at the tip

JSP – Jacketed Soft Point – a bullet that is jacketed in metal, but with exposed lead at the tip.

LOP – Length Of Pull – the distance from the face of the trigger to the end of the buttstock.

LPK – Lower Parts Kit

LW – Lightweight

M16 – The original full-auto military version of the AR-15 rifle.

M4 – A 14.5″ barrel carbine version of the M16A2.

MAP – Minimum Advertised Price (A price below which retailers are prohibited from advertising a product. Not all manufacturers/distributors enforce MAP policies, and even when they do, retailers are not legally prohibited from selling below MAP.)

Mil Spec – Military Specification. A United States defense minimum standard, often called a military standard, “MIL-STD”, is used to help achieve standardization objectives. Mil Spec will define shape, size, metallurgy and treatments of a firearm and firearm components. Also see TDP.

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.

MP – proof mark that indicates Magnetic particle inspection and Proof load firing has been performed on a barrel. Magnetic Particle [inspection/testing] (Magnetic particle inspection is a non-destructive steel inspection method used to ensure that a barrel, for example, is free from metallurgical defects such as cracks.

MRF – Modular Rail Forend (a rail adapter system made by Troy Industries)

MSRP – Manufacturer’s Suggested Retail Price

ND – Negligent Discharge (an unintentional discharge of a weapon that reasonably should have been forseen 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 – Sometimes used to describe the 1specified quality of an item. However refers to the National Matches sponsored by the Civilian Marksmanship program.

NSN – National Stock Number  – a unique number assigned to each item in the Federal Supply Cataloging System, including parts and accessories for military weapons.

NVD – Night Vision Device

OAL – Overall Length

OD – Olive Drab. Sometimes called ODG for Olive Drag Green or Army Green.

OD – Outside Diameter

OTM – Open Tip Match – a type of hollow point bullet designed for long range accuracy.

PAFS – Permanently Attached Flash Suppressor – generally permanantly attached in order to bring a barrel’s overall length to 16″ and thus avoid the legal restrictions on SBRs.

PDW – Personal Defense Weapon  – a compact weapon designed primarily for defensive rather than offensive operations.

POA – Point Of Aim

POI – Point Of Impact

Post ban – Typically referring to AR15′s which adhere to the 1994 Clinton Assault Weapon Ban which has since expired.

Pre ban – Typically referring to AR15′s or parts and components without restriction.

PRS – Precision Rifle/Sniper  – a precision stock made by Magpul, adjustable for height and LOP.

QCB – Quick Change Barrel.

QD – Quick Detach.

RAS – Rail Adapter System.

RDIAS – Registered Drop-In Auto Sear

RIS – Rail Interface System

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

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.

SAW – Squad Automatic Weapon

SBR – Short-Barreled Rifle (a rifle whose barrel is less than 16″ long as defined by the NFA)

SD – Shell Deflector

SMG – Sub Machine Gun

SP – Soft Point – a bullet whose lead tip is exposed rather than jacketed in a harder metal.

SPC – Special Purpose Cartridge as in “6.8 mm SPC”.

SPR – Special Purpose Rifle – precision rifle with 18″ free floating match barrel upper.

SS – Stainless Steel

TDP – Technical Data Package – the collection of drawings, engineering notes, etc. that describe in detail the design and construction of an item.

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)

USGI – United States Government Issue – Usually is used as a reference to magazines.

VFG – Vertical Fore/Forward/Front Grip

AR15 Design Ideas

AR15 Design Ideas

15. AR15 Basic Design Ideas & Summarized and Condensed

Design ideas…

Home Defense

Three gun low recoil standard carrier, 18” barrel w/ mid length gas system, standard buffer spring with H2 buffer, muzzle compensator


Three gun – fast cyclic rate (low mass carrier, standard springs and buffer, adjustable gas system, muzzle compensator.

AR15 Upper Receiver Parts

AR15 Upper Receiver Parts

14. Other than the major parts, AR15 barrel, bolt carrier group etc… you will need less thought for the remaining parts such as the charging handle and forward assist to complete your AR15 build. Dust Covers are also an optional accessory on some AR15 upper receivers.

The dust cover on the AR15 allows the bolt carrier group and inner working of the rifle to remain relatively free from blown in dust and debris. This dust cover very handy in sand-box type environment and opens automatically as the action cycles.

The forward assist, while not present on all AR15 upper receivers, helps push the bolt carrier group into battery. This option would be handy in a tactical or self defense use AR15. A simply bump forward on this assist button is usually enough to force the bolt closed of dust or grime are present in the chamber or action.

These parts can sometimes be found in Upper Receiver Parts kits.

Charging handles may require a little more thought. The mil-spec charging handle is forged aluminum and has the release latch on the right side to be operated right handed. An ambidextrous charging handle may be operated either right or left handed.  If a scope is to be used, a “Tactical” latch is suggested to more easily clear the scope when operating the charging handle. While the mil-spec charging handle is forged some manufacturers are using steel handles for extra strength while others are using weaker 6160 aluminum which is more prone to bending while operating the AR15 charging handle.

A delta ring is not always used, but is used with standard mil-spec hand guards. The barrel nut is always necessary but the style of barrel nut may vary based on the hand guard that you use.

AR15 Sight Options

AR15 Sight Options

13. When discussing sights, normally the discussion revolves around iron sights, often called Back Up Iron Sights (BUIS).  Although red dot and holographic sights are also available, they are exempt for the discussion of this article.  Iron sights for the AR15 are available fixed or flip up styles.

A Front Sight Base (FSB) is one type of fixed front sight.

If using a red-dot or scope you may or may not wish to use BUIS on your AR15. However in a tactical situation it is usually suggested to have the backup sights incase your primary sight becomes non-functional.   The general rule of thumb in this case is to run fixed sights as backups if using a red dot or holographic sight, and flip up sights if using a scope.

AR15 Hand Guard Options

AR15 Hand Guard Options & Free Float Tubes

The hand guard’s purpose is to protect the shooter’s hand from the heat of the barrel. The options of hand guards are seemingly endless from an almost infinite number of manufacturers.  Two things to keep in mind is the hand guard will either be traditional, sometimes called drop-in, or will be free float. Some hand guards will have rails, while others will not.

AR15 Muzzle Device Options

AR15 Muzzle Device Options

10. Muzzle Attachments will help the user to customize their AR15 to their shooting needs. The 3 basic options are compensators, flash hiders,  or crowned muzzle. A compensator, AKA muzzle brake, is used to help control muzzle climb by venting gasses to the top and side of the barrel but does little to hide flash. Most muzzle brakes have holes or slots perpendicular to the barrel. A flash hider doesn’t help much with muzzle climb, though the A2 style bird cage flash hider does have a solid bottom. The real purpose of a flash hider is to help prevent night blindness due to flash from the muzzle, and also help mask the shooter’s location.  A flash hider will have slots parallel with the barrel. A crowned muzzle means the very tip of the barrel is precision cut to perfectly exhaust gasses in all directions (360 degrees) and reduce the chance than the bullet’s trajectory will be affected by directional gas flow.  Sound suppressors may also be attached to the muzzle where allowed by law and with ATF permission.

What muzzle device is right for you depends on the purpose and use of your rifle.  For example most competition three gun shooters usually run compensators.  Flash hiders are perfect for home defense or tactical applications since shooting will likely occur indoors and/or during low-light conditions.  Many bench rest shooters and hunters alike prefer crowned muzzles. Though some hunters, especially those shooting large caliber ammunition, may opt for a compensator instead.

Also before choosing a muzzle device, it is important you know the caliber of your barrel as well as the threads of the barrel.  You wouldn’t want a 22 caliber muzzle device on a 30 caliber barrels. Also a 1/2″x28 threaded device won’t fit on a 5/8″x24 threaded barrel.   1/2″ x28 and 5/8″x24 are the two most common thread sizes on the AR15 barrel, however 9/16″x24 and some other proprietary threads are also sometimes used.