Firearm History

15 Common Firearm Terms and What They Mean

Firearm Acronyms

AR, MOA, BP… what’s with all the lingo?

If you’re new, you probably already noticed that there’s a bunch of weird words tied in with gun ownership. It basically feels like another language.

I don’t blame you. With the teens these days saying random things like BRB or WYM, it can get confusing trying to remember all of these acronyms.

That is why I present you with this nice and short list of the top 15 firearm acronyms and other terms.

Let’s get right on to it, shall we?

Common Firearm Terms

Here are 15 popular terms used in the firearms industry and what they refer to. Some can mean a few different things, so it is best to use context to help determine how the term is being used.


ArmaLite Rifle-15. A lightweight, semi-automatic rifle made in different types of models. The name comes from the firearm’s original manufacturer: ArmaLite, Inc.

Assault Rifle

A selective-fire rifle used by the police force or military. Can be semi or fully automatic. Fires reduced-power ammunition and is usually fed from a large box magazine.

Assault Weapon

A political term that can be defined in a variety of ways depending on which source you look up.


A firearm that fires multiple bullets as long as you keep holding down on the trigger (can also be referred to as a “machine gun”). Difference between an automatic and a semi-automatic gun: semi-automatics fire only a singular bullet every time you pull/hold down the trigger (ex: AR-15).


Black Powder. Previously known as gunpowder. It produces a lot of smoke when ignited and is less powerful than the modern smokeless powder.


Projectile that the gun shoots out. Usually made from material like lead or copper.


The bullet’s diameter. Measures as fractions of an inch. It also tells you what size of ammunition that the firearm can fire. Used for rifles and handguns.


No, stop it. Don’t give me that look. Of course I’m adding this to the list. Typically, this is a device that uses an explosive charge to shoot a projectile. So, rifles and pistols go underneath this definition, but not air guns. However, there are some legal jurisdictions that classify air guns and bows as firearms, but they are not traditionally considered as such.

Firing Pin

This needle-shaped thing strikes the primer and helps ignite the powder, causing the bullet to shoot out.


Like a caliber, but for shotguns. It’s the diameter of the inside of a shotgun’s barrel. Gauge is determined by the amount of lead balls that are the same size as the bore that it would take to weigh a pound.


Holds cartridges under spring pressure until they are ready to be fed into the gun’s chamber.


Minute of Angle. Measures the precision of a rifle and can also be used as a measurement when you shoot long distances. Can also describe the size of a red dot’s reticle size. Yes, yes. I know that’s a lot of definitions. But if you’re confused about which definition someone is referring to, just use context or simply ask.


Mechanism used to prevent the gun from being fired (but don’t always rely on the safety when using a firearm). This can be manual with a switch you press or passive with something that blocks the firing pin.


Slang term for a round’s leftover casing after being fired. Also used to describe a shotgun’s ammunition.

Waiting Period

The legally mandated time interval where you buy a firearm and then received it. Between seven to twenty-five days. This is state-specific and some states do not require a waiting period at all.


Well, that’s it folks! If you didn’t see the term you wanted or are still curious, don’t forget to check out our complete dictionary of standard firearm terms.

When you’re first getting into firearms, I know it can seem like an overwhelming amount of information to take in, but learning the lingo is the first step. Till next time!

Confused about any firearm acronyms? Let us know in the comments down below!

About the Author:

Richard Douglas

Richard Douglas is a firearms expert and educator. His work has appeared on large publications like The National Interest, Daily Caller, American Shooting Journal, and more. In his free time, he reviews optics on his Scopes Field blog.
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (18)

  1. I’m not a novice and have been a gun owner and a huge advocate for many years. I appreciate the refresher and will not look to your words for the precise interpretation to satisfy every person that reads this. I’m just glad you’ve taken the time to give a general term for these acronyms for our much welcome newer gun owners looking to learn the lingo and exercise their 2nd amendment rights.


  2. @Force Recon Marine

    I don’t disagree with what you are saying at all. My only point was as laws are written now there is not a waiting period in every state. To say that there is or there isn’t is a lie either way.

  3. Changing the line to read, “Typically, this is a device that uses an explosive charge to shoot a projectile,” says the exact same thing but removes any question about on which side of the muzzle the explosive charge is used. My first two attempts at reading about “a projectile with an explosive charge,” just weren’t giving me a nice warm feeling.

  4. Re: MOA. As an engineer by training, I have occasionally used target strikes to explain the difference between “accuracy” and “precision”. MOA is the latter, and is akin to grouping of shots. Accuracy, on the other hand, is the systematic deviation of the strike points from where you intended them to land. We shooters adjust, or calibrate, for accuracy. I demonstrate the two concepts with four examples: precise/inaccurate, accurate/imprecise, inaccurate/imprecise and precise/accurate. Here’s to every shooter seeking the final example.

    So, with all due respect, MOA is the precision of a firearm, however that is defined.

  5. Firstly, thank you for doing this. There are more 1st time gun owners in 2020 than probably any other 3 year period in our nation’s history.

    A non-politicaly-charged mechanical introduction is exactly what is needed to educate these folks. That is exactly what you provided. So again, thank you for putting this together. Now hopefully all of the new 1st time gun owners will find it.

  6. @ Phil Of the twenty-seven words contained in our Second Amendment “Our founding forefathers were absolutely magnificent and incredibly smart and they didn’t write it in lawyer-ease,” nowhere do I see any caveats allowing for the feral government, any government state or local the ability or responsibility to restrict my God given and constitutionally protected right of self preservation. There are no clauses allowing for background checks, waiting periods, psychological profiling, permitting, or the registration of any firearm to anyone!

    Most of our elected politicians in Government don’t recognize the Clause “the right of the “people” to keep and bear (carry) arms ‘SHALL NOT BE INFRINGED’ However, I do see plenty of elected officials who would just as soon try and TAKE our God given right by usurpative fiat while at the same time refusing to abide by their oaths of office.

    We go back to the simple question of “What part of “shall not be infringed” do these Leftopathic Corruptocratic Globalists not understand”? Any law restricting ownership of any firearm written since 1791 is UNCONSTITUTIONAL and therefore technically unenforceable ! Guns have but two enemies, RUST and Politicians!!!

    As for the NICS Universal background checks, They are the opposite of being effective and a solution to a problem that doesn’t exist. It’s already a crime to sell a firearm to somebody who is not legally allowed to own a firearm, whether one goes through a background check or not, that is already a crime.

    The NICS background check database is “faulty” and “racially biased,” in that minorities are more likely to share a surname with someone else who may have a criminal record.
    Consider for decades now our Bill of rights has been under attack. Again I want to reference the Amendment that the framers intended to guarantee compliance of the other nine amendments, our second amendment.

    I am curious to find out just how many politicians would be willing to place the same caveats as they have on our Second Amendment or any other amendment e.g. file a form and wait several days so one can exercise their first Amendment right to exercise free speech – file a form and wait several days to exercise their third amendment rights protecting us from unreasonable search and seizure. Or the ninth amendment that states that there are other rights that may exist aside from the ones explicitly mentioned, in the Bill of Rights even though they are not listed. Meaning they can be violated. The proverbial political foot is in the door, and APATHY from the American people is allowing the door to usurpation to be thrown WIDE open as if it wasn’t there.

    Regarding Red flag gun confiscation laws; they violate the Fourth Amendment.
    If the government takes somebody’s God-given rights because they think that a person might someday commit a crime, then we enter into the realm of dystopian science fiction movies. Whether one is an ardent defender of the Second Amendment or not, all of us should be concerned about the implications of the Fourth Amendment and due process. The fourth amendment is a foundation of our country.”

    Democrats don’t care about keeping people safe. For Democrats, this issue is about emotion. They’re appealing to emotion and not reason. If they were appealing to reason, they would know ways to keep people safe and that, to quote a book, ‘more guns equal less crime.’ But also for the Democrats, it’s about paying back their donors. Soros and Bloomberg are going to want to get what they paid for, and what they paid for is disarming our society.”

    No one but God can dictate policy to me and my family and I will do whatever it takes to secure my liberty and the liberty of my fellow patriots. Stand in my way try and usurp my rights or otherwise enslave me, you should be prepared to back your actions up with your life as I am prepared to do likewise!!
    There comes a time when you have to stand for the Constitution or die by legislation one usurpative bill at a time.

    I will offer this little but important lesson in history – The reason Americans should be aggressively fighting against gun control is because armed people will not willingly load themselves in boxcars or FEMA camps!

    “Laws forbidding the carrying of arms disarm only those who are neither inclined nor determined to commit crimes.” Thomas Jefferson quoting Cesare Beccaria

    If one refuses to fight for what one has then one shouldn’t cry over what they lost!!!

    Libertas est, non liber – mercedem mihi portionem substantiae sumptus
    Libertas inaestimabilis res est
    Celer Silens Mortalis

  7. @Bo Never try and figure out what goes on in a LIEberal’s head for they have no brain to begin with! as you hinted at LIEberals have ZERO common sense but react upon their “emotional state” cancelling any “common sense” any NORMAL person employs. Bottom line Lieberals have a NEVER ENDING SUPPLY OF STUPIDITY!!

  8. IMHO, The terms Assault Weapon and Assault Rifle are both Political Terms used by the media and Gun Grabber politicians to portray the owners of such firearms as deviant killers. I ran a shooting range and never heard staff or a customer refer to AR type weapons with these terms.

    If you are going to list Automatic as a firearm type, why did you leave out Semi-Automatic. Semi Auto is vastly more prevalent. You should also mention that Automatic weapons can only be owned by civilians with a rather extensive background check and an expensive firearms permit.

  9. Gauge is the number of lead balls of the diameter of the barrel that it would take to make one pound. 12 gauge takes 12 balls of that diameter. 20 gauge takes 20.

  10. In some jurisdictions, definitions defy logic, allowing air guns and BB guns to be legally classified as firearms. Norman Oklahoma is one of those. Sometime in the last year or so, it was reported in the local newspaper, the illustrious Norman Misprint, (I’m sorry, did I say that?) It is called the Norman Transcript, and the article stated that someone shot and killed a red fox with a pellet gun. It was further reported that if the offender was caught, there could be felony charges of discharging a firearm inside city limits filed against the offender.
    When I called the Norman PD to question that statement, I was informed that, at least in Norman, BB guns and air guns were defined as firearms, even though there was no “fire” involved with those DANGEROUS weapons. I cannot speak for the rest of Oklahoma, where I would hope common sense might be found. But, Norman is a town that prides itself in its liberality. I would love to be able to afford to move.
    But, you have to understand that in the last week or so, our city council has made significant cuts to the PD budget after local protestors called for complete defunding of the police. They just cut four positions from the police budget, and they will be working to recruit more minority officers, which will be difficult as they don’t have the positions open to hire those new officers. Never try to figure out how liberals think, they cannot, they only feel.

  11. There are many firearms that do not have a mechanical safety, such as most revolvers. However most of them do have some sort of hammer block. Gauge of shotguns are based on the number of round lead balls the size of the barrel that can be made from one pound of lead….. except the 410 bore, which is actually a caliber (.41 cal) rather than a gauge. In some states, when an air gun or even a bow/arrows are used in a felony crime can be considered a ‘firearm’. No ‘waiting period’ is constitutionally a legally mandated time period.

  12. There’s also “Mil-Spec” when comparing it to “Mil-Std”! To be Mil-Std, the firearm has to pass above 51% a Mil-Std-810G “Environmental Engineering Considerations and Laboratory Tests of three testing groups of twenty-four categories each. Fifty percent or lower is considered Mil-Spec…

  13. Not to nit pick too much but I think that your safety definition should be changed. There are guns where the safety only locks the hammer. Heck cross bolt safety’s on Marlin Lever Actions only like the firing pin. The hammer and trigger functions as normal with the gun on safe.

    I also think that you should mention that the waiting period is state specific. There is no waiting period here in Ohio.

Your email address will not be published. Required fields are marked *

Your discussions, feedback and comments are welcome here as long as they are relevant and insightful. Please be respectful of others. We reserve the right to edit as appropriate, delete profane, harassing, abusive and spam comments or posts, and block repeat offenders. All comments are held for moderation and will appear after approval.

Discover more from The Shooter's Log

Subscribe now to keep reading and get access to the full archive.

Continue reading