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Reader Anner writes:

True Believers get all wrapped up in proper firearms terminology. Avoid that next lecture from the old coot behind the counter by studying this partial guide to proper firearms terminology:

Caliber – The diameter of the firearm’s bore, expressed as a fraction of an inch. “.30 caliber” is 3/10 of an inch wide.  Depending on manufacturer’s specifications, this may denote the diameter of the bullet, cartridge mouth, barrel lands, or barrel grooves. Europeans generally measure barrel lands, while American manufacturers use barrel grooves (which is usually the actual bullet diameter).  When ammo manufacturers create a new cartridge, they need it to sell. They will often choose a name that does not accurately describe its actual size. For example, .223 Remington is actually a .224” bullet; .300Blackout is actually a .308” bullet. Reference a reloading manual or the manufacturer’s website for accurate specifications . . .

XXmm – A metric version of denoting bullet diameter. 9mm is the diameter of the bullet, barrel, or related object. Again, Europeans differ in what they actually measure.

Caliber vs. XXmm vs. What ammo do I buy? – When in doubt, look at what’s imprinted on the barrel and purchase ammunition identical in nomenclature. Be wary of +P, Magnum, or Short Magnum designations (see below).

Cartridge – The entire components of a loaded case, primer, powder, and bullet.

Bullet – The projectile that exits the barrel under pressure from the burning powder and expanding gases.

Shell – Also called the ‘case’; the container that houses the other components of a cartridge. Among shotguns, ‘shell’ is analogous to ‘cartridge’.

Primer – The small, circular component at the rear of a cartridge struck by a firing pin, which detonates the powder.

Brass – The empty case or shell.  Common use is to refer to the reloading component as “brass”, or a fired round as “spent brass.”

Magazine – The device that stores cartridges until the firearm’s action positions them into the chamber for firing.  Most repeater firearms except revolving handguns use a magazine. Bolt-action rifles that hold extra cartridges internally still technically use a magazine, though it is not detachable. Lever action rifles with an ammunition tube below the barrel also use a magazine; it is a tube magazine.

Clip – This is different than a magazine. A clip is a small metal piece that secures loose ammunition for loading into a magazine. One example is the M1 Garand en-bloc clip, which holds eight rounds of .30-06 ammunition for loading into the Garand’s internal magazine. The M-16 family of rifles is capable of using 10-round stripper clips to feed the larger 20-round or 30-round magazines, though this practice is not common. Very few firearms use a clip.

Single Action (SA) – The hammer is pre-cocked and ready to fire upon lightly pressing the trigger. Handgun examples include the Browning Hi-Power, 1911, and Colt Single Action Army. The vast majority of rifles and shotguns are single action, including bolt-action and lever-action rifles. Single action firearms generally have a light trigger pull and short trigger travel, necessitating extra caution.  Many SA firearms incorporate additional safeties, all secondary to proper gun handling.

Double Action (DA) – Pulling the trigger both cocks the hammer and releases it to fire.  Examples include Smith & Wesson revolvers (though, if you cock the hammer manually it turns into a single action).  DA triggers are generally heavier and require longer trigger travel to fire as compared to SA firearms.

DA/SA – Any firearm that offers you the option of both DA and SA fire.  Two common examples:  A S&W revolver has an exposed hammer, which allows you to cock the hammer then pull the trigger (SA), or to simply pull the trigger and let the trigger pull back the hammer before firing (DA).  Also, most Sig-Sauer and HK pistols are DA on the first shot but revert to SA fire once the slide has cycled.

Decocker – Most DA/SA pistols also incorporate a lever that safely lowers the hammer from SA mode to DA mode.  HK builds this into the safety lever, while Sig-Sauer has a separate decocking lever.  This can be useful after a stressful situation, in which you’ve fired and wish to return to the heavier trigger pull of DA mode to prevent a negligent discharge.  As always, proper firearms safety is more important than a mechanical device.

Striker-Fired – Just to confuse the matter, some pistols do not use a hammer at all.  Instead, they use a ‘striker’ that acts as the hammer.  The striker is captured by a spring, partially cocked when the slide cycles, and fully cocked and released when the trigger is pulled.  For the purposes of handling, treat these as SA.  However, the trigger often feels midway between a DA and SA.  Examples include Glock pistols, Springfield XD series, and S&W M&P series.

Handgun – Any firearm fired using your hands only, without a stock for securing against your shoulder.  Some handguns can be very large, requiring both hands to hold.

Pistol – A semi-automatic handgun.  Pistol is commonly misused to reference all handguns, including revolvers.

Revolver – A handgun with a rotating cylinder that holds the cartridges.

Derringer – A small double-barreled handgun.  Offered by various companies from .22LR to .410 shotgun, derringers are limited in value due to a low capacity and terrible ergonomics.  They can be dangerous if mishandled, due to a heavy hammer cocking motion, single-action trigger, and short barrel.

Sidearm – A police/military term for a supplementary weapon.  It usually denotes a handgun, but can be a shotgun, secondary rifle, etc.  Sidearm is not in common use outside of police or military units.

AR = Armalite – Eugene Stoner designed the rifle that led to today’s wide range of M16-inspired designs.  Mr. Stoner worked for Armalite, an aerospace manufacturing company.  The Armalite firearms company still exists today, producing high quality rifles.  AR was originally a reference to the Armalite name, but has been hijacked as ‘assault rifle’, a fictitious reference to the various forms of the parent AR-15 rifle.

MSR = Modern Sporting Rifle – In response to the creation of the terms “assault rifle” and “assault weapons”, in which a name and cosmetic features played a role in legislation passed by congress (most notably the Assault Weapons Ban of 1994), gun rights supporters pushed back.  Given that the AR platform is ideal for various sporting uses, such as varmint and hog hunting, the term MSR emerged to reflect the AR’s common use as a hunting platform.  Keep in mind, the 2A has nothing whatsoever to do with hunting or tradition—it is squarely aimed at preventing government tyranny—but in supporting 2A, words matter.  An uninformed voting public will latch onto words, and scary words drive votes.

SS = subsonic – Most modern cartridges fire a bullet at supersonic speeds, creating a ‘crack’ as the bullet leaves a mini-sonic boom in its wake.  Subsonic loads are much quieter out of a rifle, and slightly quieter out of a handgun.  Except for +P loads, standard 45ACP loads are generally subsonic out of a handgun.

LRN = Lead round nose – LRN bullets are ideal for shooting steel targets, as the soft lead splatters on the target.  FMJ rounds tend to deform the steel, or invert ricochet at the shooter.  This situation has killed people, so be careful of your target and your ammo.

FMJ = Full metal jacket – The core of a bullet is usually lead.  On FMJ rounds, this core is surrounded by a metal jacket, usually copper or tin alloys.  The jacket may only cover the forward section of the bullet, leaving the base as exposed lead.  FMJ rounds are cleaner to shoot than solid lead rounds, with less chance of fouling in the barrel and action, and less lead exposed to the environment.

TMJ = Total metal jacket – The entire bullet is encased in a jacket material.  For indoor shooting ranges, TMJ offers the lowest chance of lead particles fouling the air.

Plated – Similar to TMJ, plated bullets are lead cores with a thin coat of metal on all sides.  Instead of a thick metal jacket, the plating is thin but effective.  Plating is just as clean as TMJ when cycling and firing, but much cheaper to produce.

HP = hollow-point – HPs are designed to expand on impact for more tissue/target damage and less chance of over-penetrating and striking something on the other side of the target.  HPs are suitable for hunting and self-defense.

+P – Standard pressure rounds are listed under SAAMI specifications for maximum chamber pressure, expressed in PSI.  Loads that exceed these standard pressures are denoted +P.  Some loads are rated higher at +P+, though this designation is not recognized by SAAMI and carries no manufacturer guarantee of safe function.  Not all firearms are designed to handle +P loads; the instruction manual and barrel of the firearm should clearly communicate this information.  +P loads can provide a meaningful increase in muzzle velocity, potentially translating to better terminal performance.  However, there is a compromise:  +P loads also produce more muzzle blast, recoil, and wear on the firearm.  If you intend to carry +P loads, test them thoroughly in your firearm for reliability and accuracy.  In semi-automatic firearms, you may consider heavier recoil springs to counter the increased slide cycling speed.

Magnum – In French champagne country, a magnum is a unit of measurement.  It is larger than a standard size champagne bottle.  American firearms manufacturers adopted the term as they experimented with modern smokeless powders, most notably in the 1930’s while developing the .357Magnum.  The large increase in chamber pressure necessitated a distinction for rounds developed with modern powders.

This can get confusing.  Standard pressure for a .357 Magnum is vastly different from standard pressure for a .38Special (the parent cartridge from which the .357 Magnum was developed).  Magnum doesn’t just denote a change in pressure, such as the designation +P.  It denotes an entirely different cartridge.  .357 Magnum cases are slightly longer than .38Special cases.  The size difference doesn’t mean much; it was a safety feature to avoid loading a .357 Magnum cartridge into a firearm designed for .38Special.  However, the .357 Magnum is developed with more powder as its standard load.  You could load a .38Special to the same pressure as .357 Magnum (there’s plenty of room for that much powder).  However, doing so will split the case (case walls are thinner) and likely harm the shooter or firearm.

To further confuse the matter, some older cartridges are offered in +P.  In a .357 Mag revolver, you can fire .38Special, .38 Special+P, or .357 Magnum (as well as some ancient cartridges, such as .38S&W Long).  However, a .38Special revolver will denote if it’s rated for +P.  If not, stick to standard pressure loads.  If it is +P, you can fire .38 Special or .38 Special +P, but not .357 Magnum.

Bottom-line:  Purchase ammunition identical to the marking on the barrel, or thoroughly research other safe options before pulling the trigger.

Short Magnum – In the late 1990’s, Winchester experimented with taking large cartridges, such as .300WinMag, and generating the same ballistics out of a shorter, fatter case.  Such cartridges, such as the .300 Winchester Short Magnum (.300WSM), provide shorter and lighter actions to cycle the round, decreasing the overall weight and length of the rifle.  However, WSM and WSSM (Winchester Super Short Magnum) cartridges are not interchangeable with their parent cartridges.

FTF – Failure to feed – A malfunction that occurs when a firearm jams as it attempts to insert a new cartridge into the chamber.  Most FTF problems are due to cheap or broken magazines.  Quality magazines from reputable manufacturers fix this issue.  If the magazine is not at fault, a dirty/unpolished feed ramp, poor quality ammunition, or more complex issues may exist.

FTE – Failure to extract – Similar to FTF, but the failure occurs as the fired shell does not properly extract/eject.  This is usually related to the extractor and ejector assemblies, either of which may require a spring change or polishing.  In both FTF and FTE situations, online videos and forums provide excellent support from others who have had similar experiences.

Barrel porting – Holes drilled directly into the barrel between the 11 and 1 o’clock positions.  The holes direct expanding gases upward, reducing muzzle flip and/or perceived recoil.

Muzzle brake – A muzzle device, usually detachable, with holes, vents, fins, etc. that direct gasses rearward to primarily reduce recoil.  Muzzle brakes send a sharp shockwave of gas to the shooter’s rear quarters, impacting those standing nearby.  Muzzle brakes may also feature vertical holes to reduce muzzle flip, confusing the distinction with compensators.

Compensator – A muzzle device, possibly detachable, that directs gasses upwards to reduce muzzle flip.  A compensator may borrow some muzzle brake features and reduce recoil.  The line between muzzle brakes and compensators can be blurry at times.

Flash hider – A muzzle device, usually detachable, that dissipates unburned powder as it exits the muzzle.  Unburned powder commonly burns just as it leaves the barrel, producing a fireball or flash.  Flash hiders send this powder in specific directions, to mitigate the visual signature of a gunshot.  Flash hiders can be useful when hunting near dark, to avoid blinding the shooter.

BUIS = backup iron sights – Many modern rifles and some shotguns now only arrive with a picatinny rail and no open sights.  A common AR term is COR, or carbine/optics ready.  For a hunting rifle, a scope is adequate.  For a defensive rifle, where a dead battery on a red-dot optic can render the firearm nearly useless or dangerous, BUIS are essential.  Metal BUIS are expensive and heavy.  I recommend the MagPul polymer BUIS.  They’re cheaper, lighter, and tough.  I’ve used them on ARs and shotguns to great effect.

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  1. I remember buying a cleaning kit for my first handgun, a ruger Alaskan .454. Took me forever to build up the courage to ask if the .45 caliber kit would work for my .454, the look I got from the grizzled old s.o.b behind the counter was priceless and made me feel like a true mongoloid. That motivated me to do my homework on the internet before asking anyone at a gun store any damn thing. Now I feel confident in engaging in most general firearm conversations, but like most disciplines, the more you learn, the more you realize you don’t know. Be nice to a noob.

    • Think how much more in sales that s.o.b. would have had were he not such a prick. Think how much farther along in acceptance the entire gun industry and shooting sports in general would be without guys like that.

      It should have been like buying a vacuum cleaner or a computer. Heck, even the a car salesman tries to be nice about these things, at least in front of your face.

      “Hey mister, that’s not a dumb question at all. Let me explain… Would you like a bag for your purchase? Hope to see you back in my store soon!”

      • I 2nd that. Idk why customer service is different in some armories or gun stores. I just wanna love what you love man

  2. Anner,
    You could have skipped the Magpul commercial at the end, and there really should be a space between .357 and Magnum.

    One other thing: Caliber is a whole lot more than diameter. It’s a designation for a particular cartridge design with a whole slew of industry standard specifications. a .22-250 an a .223 Remington cartridge have the same bullet diameter and can use the same bullets, but they are very different calibers.

    Other than that, I think you did a nice job.

      • Agreed. Some, such as the .30-06 are due to the year of introduction (1906), others are referring to stuff I don’t know. I’d like to learn more…

        I intended to explain caliber as the unit of measurement. As I understand it, a name such as .22-250 conveys a .22 caliber bullet (actually .224, but hey). Does caliber really refer to the whole name .22-250?

        • No. The .22-250 is the same “caliber” as a .223, which is to say, they both use .224″ diameter bullets. I know that’s going to cause a brain rupture for many people, but there it is. I’m just telling you the facts – the .223 Remington uses bullets that are .224″ in diameter.

          The “-250” part of the “.22-250” nomenclature comes from the wildcat heritage of the .22-250, which is that the .22-250 uses a necked-down .250 Savage case. The .250 Savage, in turn, tried to create their own nomenclature for this round by marking it as “.250-3000” or “.250/3000” because the .250 Savage, loaded with an 87 grain bullet, was the first rifle round to exceed 3000 feet per second muzzle velocity.

          Other example of this sort of wildcat convention can be found in “.30-378″ (a .378 Weatherby necked down to hold a .30 caliber, or .308” diameter bullet), and then you can find even the morphodite designation of “6.5×284,” which is a 6.5mm bullet (0.264″ diameter) on a .284 Winchester case.

          Where wildcat cartridges are concerned, there’s little regularity in their naming convention. The .22-250 was one of the first modern wildcat cartridges made into a popular commercial round.

          I could go on for a day and a half trying to explain all the wildcat names out there.

        • So… if someone asks what caliber my rifle is, I could say “It’s a .223 Remington” and I would be wrong?

        • so the other suffixes in hyphenated calibers like .32-20, .32-40, .45-70 and .45-90 refer to black powder volumes originally? in grains?

        • Nice article.

          Cartridge / caliber names are really a combination of barrel diameter and marketing. A .44 Mag is really a .429 caliber, but .44 sounds cooler. DG is right on the .223 being a .224, and the .22-250 also being a .224. They can fire the same bullet, but the .22-250 will push it a lot faster. Some simplification could be made by differentiating between a cartridge name and designation versus bore diameter.

          The .300 Blackout, .308 Winchester, 7.62 NATO, .30-06 Springfield, and .300 Winchester Magnum can all shoot .308 the same 150 grain .308 diameter bullet. There’s no way they could safely be shoot from the same chamber, as the brass is different in length and diameter.

          Of course new shooters should start off by just putting .22 Long Rifle into .22 Long Rifle, 9mm into 9mm, etc. There are safe combinations and there are explosive ones.

        • If you’re shooting a .223 Remington, or a .222 Remington, or a .22 WMR, or a .22-250, the caliber of your bullet is 0.224″.

          The cartridge you’re using is a .223 Remington, .222 Remington, .22 WMR or .22-250.

          re: the question on black powder cartridges – yes, those -XXX designations were powder charges in grains. A further refinement might be “.45-70-405” which was the bullet weight in grains as well.

          Some BP cartridge rifles called out the length of the case in inches in other designations.

        • Yes your right it can refer to the year adopted.
          Or it might refer to the charge of black powder As in .38-40, .44-40, 45-70.
          Or it can be the length and type of the case. 7.62x54R, 7.62×39, 8x56R
          some time a name is added as in 9mm Styer-Hann, .9mm Mauser export, .9mm Japanese rimmed.
          It gets real crazy . .38 Special can also be correctly described as .9X29R , but
          .38 Smith & Wesson is something different.
          .380 of today can be called .380 ACP, 9mm Browning, 9mm Corto, 9mm Kurz, 9mm Short, 9×17mm and 9 mm Browning Court, or .9mm Skurt. but it is not the same as a couple different obsolete .380 revolver cartridges .
          The rhyme and reason to it is often hard to see and dependent on who you ask.
          I am sure this was way more than you wanted to know. I’m just trying to being a Mr. Know it all

    • I don’t really think that mentioning Magpul was a commercial. It was a short note and if Anner believes it’s a good product no harm mentioning that I think.

      Good article!

      • Robby… .9s dude? And I agree magpul was probably used as an example not an endorsement. Very well written and concise enough to be bookmarked as a go to when I need a guide for newbies

        • I miss spelled one of the .380 names. .9 mm scurt is correct and not skurt.
          It is the word used for the caliber marking on Romanian military contract Beretta model 1934 pistols.
          While not a common pistol, they are not as rare as one might think.

    • I’d like to note that the numbers in both .38 Special and .44 Magnum are artifacts of earlier parent cartridges. In the case of .38 Special, it’s really a .357 caliber. This is because .38 Special is derived from .38 Long Colt, which in turn was derived from .38 Short Colt. Early .38 Short Colt used a heel based bullet that was the same diameter as the cartridge case, like an oversized .22lr. By the time .38 Long Colt came around, Colt switched to a smaller .357 caliber bullet in a lengthened .38 case. S&W created .38 Special by lengthening the .38 Long Colt and using the same .357 caliber bullet. They finally gave a proper caliber designation when they lengthened .38 Special to create .357 Magnum.

      .44 Magnum followed a similar history. This time the parent case was .44 American, which also used a true .44 caliber heel based outside lubricated bullet. Imperial Russia approached S&W for a version of their Model 3 top break revolver in .44 caliber. But they wanted an inside lubricated bullet in the same case as the .44 American. So S&W developed .44 Russian, which used a smaller .429 bullet in the .44 American case. When S&W made a new smokeless powder .44 cartridge for thier New solid top hand ejector, the .44 Russian was lengthened to create .44 Special. And .44 Special was lengthened to create .44 Magnum in the 1950’s. Even though .44 Russian, .44 Special and .44 Magnum are all actually .429, S&W didn’t change to the actual caliber designation the way they did with .357 Magnum.

  3. Nice … and very complete explanation.

    I sure hope TTaG posts this under their “Guns For Beginners” tab!

  4. Pretty accurate except for the term pistol. Pistol is interchangeable with handgun. Examples of other pistols are single shot, multi barrel and revolving pistols. Semi auto is a sub-.category

    • No, the article has it right. ‘Pistol’ is often mistakenly used interchangeably for ‘handgun’, but it is not the same.

      • Pistol and handgun are not completely synonymous, but the term “pistol” has been around for centuries and was commonly used long before the advent ammunition cartridges or semi-automatic handguns.

      • It’s half right. A pistol is a handgun with a single chamber. Semi-automatic handguns are all pistols, except for exotic pieces like the Webley-Fosbery revolver. However, there are also single-shot handguns, including antique muzzle loaders, that qualify as pistols.

        • You can blame the National Firearms Act for defining a pistol as a handgun having a chamber integral to the barrel. It was all about creating definitions necessary for regulation. Before that, any handgun was a pistol. Kind of like how modern sporting rifles suddenly became “assault weapons” in the 1980’s. The reason for a specific designation between “handgun”, “revolver” and “pistol” is because all three were tax stamp items in the original draft. The regulation of short barreled rifles and shotguns was to prevent people getting around the handgun ban. Ironically, the handgun ban did not survive congress but the regulation of sawed off long arms did.

        • And if you go back to the 14th century “handgonnes” were long guns – the only firearms of the day that could be carried in your hands.

  5. But, what’s the proper name for the folding thing that goes up?

    Other missing entries: “Inexcusable Instrument of Death”, “Macho-Totem”, and “Manhood Extension / Substitute”.

    Get on that, would you?

  6. “Pistol – A semi-automatic handgun. Pistol is commonly misused to reference all handguns, including revolvers.”

    Nope – it includes more than just sem-autos. By necessity, it includes pre-revolver, single-shot pistols (see “Pirates of the Caribbean”, etc.). The common misuse it to think it limited to just semi-autos, whereas it’s really just an older terms for “handgun”.

    Derringer – A small double-barreled handgun.

    Nope again – a derringer is defined by its small size, and the fact that it does not have a reloading mechanism – while a derringer can have one or more barrels, each barrel only has only one cartridge loaded, and reloading much be accomplished by hand.

  7. Clipazine: thingies that holds the pointie things.

    Thing That Goes Up: barrel shroud.

    Ghost Gun: Firearm that disappears when you insert the Clipazine.

    Cop Killer Bullet: Any projectile that exceeds 300 feet per second. Can include spit wads that have been frozen, and some v-wads.

    What am I missing?

  8. Maybe this is more “intermediate” than “beginner” but I would like to see explanations of terms like “Upper” and “Lower” and the % that are attached to them. I get that they are different parts of the modular AR-15 platform but why are so many being sold separately, what advantages/options/legal workarounds are they providing? What work is required to get an 80% part to 100%? Is this something Joe or Jane average is doing at home or is this pro gunsmithing?

    • Try searching the TTAG archives. Nick Leghorn has written some great articles on AR builds and the like. Him and Jeremy S also walk through some of that when discussing imported firearms and 922/R compliance.

    • By law, one part of a complete firearm is considered the firearm. All other parts are accessories, such as sights or slings, even critical components such as barrels.
      The upper of an AR style firearm is not the legal part of the firearm. You can buy complete uppers just as you can buy scopes.
      The lower, without any part of the fire control group or selected or buffer tube, is legally considered the firearm by law. Note, it cannot be fired in this state because it is a hunk of sculpted aluminum.

      At some point during manufacturing, a block of aluminum becomes classified as a firearm. Obviously, a plain block of aluminum is not a firearm, and if all that was required to complete the lower receiver was dip it in water there would be no difference between a complete firearm and one that could be purchased as if it were a scope (which is how it should be, but I’m talking about existing law)

      The ATF defines any lower receiver as being more than 80% complete as a functional firearm, and hence, a license would be required to manufacture and sell the lower receiver and the buyer would need to fill out a 4473 form.

      The 80 lower, allows someone to buy a block of aluminum that is 80% closer to being a functional lower than just a plain block of aluminum.

      There is still work required to complete the lower, you have to drill out the magazine well, the fire control group well, and drill holes for all the pins. Having a drill press helps immensely and a jig is recommended if you are not really familiar with the process.

      The 80% lowers in general cost more than a functional lower, so there is no cost savings, but there are quirks in the law that drive the market.

      For example, in California, you cannot buy an AR Pistol nor an AR Pistol lower, but you can make a AR Pistol lower, so the easiest way to make the lower is to buy an 80% lower and proceed from there.

      • The ATF has no such definition of what is “80%.” The ATF works off the idea of whether or not the receiver is ready to take the fire control mechanism, ie, the lockwork for the trigger.

      • Anyone who knows how to use a drill and router can do it. The magazine well is already finished on all 80% lowers I know. Broaching it would be major PITA.
        It looks like the ATF does have some strict rules about how much must be left undone to be still considered 80 percenter. For example marking of positions of holes for pins with dimples is a no-no. One manufacturer trying to make our life easier cast part of their polymer lower in different color. You would just machine different colored plastic out and end up with nice fire control pocket. That also didn’t fly with ATF.

    • FMJ is different, and I’ll add that to the document that contains this article. FMJ is enclosed around all but the base, leaving lead exposed at the base. The explosion of powder behind that base leaves a little lead in the chamber, barrel and environment.

      TMJ is a marketing term to denote that the entire lead core is enclosed in a jacket, including the base. I included it here because it’s not as common, and may be confusing to prospective buyers. It’s more expensive, on average, than FMJ, so it’s good to smart up those that are wondering where that extra dollar are going.

  9. One nit: The term “magnum” was started in the UK, by Holland and Holland a little more than 100 years ago, with the introduction of the .375 H&H Magnum. They used the term to mean simply “a big bottle.”

    Also, the term “calibers” changes meaning depending on whether you are talking of small arms, or artillery/naval guns. In small arms, it is the plural of the word “caliber,” which refers to the diameter of the bore.

    In a naval gun (eg), “calibers” refers to the length of the barrel expressed as the number of times the barrel is longer than the bore diameter.

  10. Generally a great job. There were a few times where I was ready to call you out for defining a term with terms that needed definition, and there they were. You provided a lot of information without too much interjecting your opinion or editorializing – which a lot of writers struggle with when conveying basic facts.

    One thing I would suggest adding, since you mention it (even though it wasn’t the primary part of the definition), is land and groove. It could all fall under a “rifling” definition (along with polygonal).

    • Good point. I’ll add that. I hadn’t considered adding a section on polygonal rifling. There are some interesting muzzle velocity tests online about that.

    • The term of “+P” or “+P+” refers to a specific situation that isn’t a “magnum.”

      A “magnum” is just a marketing term, which used to mean “big hollow case that can hold lots of powder.” That said, the cartridge might be loaded to relatively modest pressures. It has become fashionable for MAP’s (Maximum average pressures) for newly designated American magnums to be over 60K PSI, but that wasn’t always the case. eg, the .300 H&H (the very first magnum) has a SAAMI spec of 58K PSI MAP, but a .338 WinMag might have a MAP of 64K PSI.

      When the term +P was invented, it was applied to existing cartridges (mostly handgun cartridges) of long history. eg, the .38 Special. SAAMI calls out the typical MAP for the .38 Special at 17K PSI. The +P loading of the .38 Special (which is in the exact same case as the regular .38 Special) has a MAP of 20K PSI – and will give you about 100+ fps more at the muzzle. The cartridges that have a +P designation tended to be older, low-pressure cartridges (.38 Special, .45 ACP, .38 Super) that, with modern powders, are capable of being loaded to higher (and sometimes, much higher) pressure levels than historically nominal.

      • In re-reading this, I realized I forgot a couple of words.

        The .300 H&H Magnum was based on the very first magnum, the .375 H&H Magnum. The .375 came about in 1912, the .300 in 1925 or so.

  11. Excellent exposition of nomenclature. I am a relative noob(maybe 5 years). Being somewhat OCD I decided to edumacate myself as much as possible. THIS would have helped 5 years ago. Good job…

    • FWW, that sound you just heard was my mind being blown! I never would have pegged you (based on your posts) as a NOOB.

        • Aw thanks guys. Hey I’m over 60 and have done this my whole life. I’m also a long-time antique dealer and learned years ago that the key to $ was knowing EVERYTHING. You should see me at the local gun shops when I know more than the young goof behind the counter. And a lot of the old ones. Like I said it helps to be OCD( my wife wants to know when I will make money at this)LOL…

  12. Nice, concise article with much useful information. May I suggest it be left open for further additions as they are suggested?

    Here are two critical ommissions.

    OFWG – Old Fat White Guy (though I prefer Old Fart White Guy – I ain’t THAT fat) – according to the gun grabbers the only group in America that is “bitterly clinging” to our guns. (In spite of NRA spokesmen Colion Noir and Dana Loesh, and TTAG’s leadership of proud Jewish heritage and diverse readership.)

    Fudd – According to the Urban Dictionary, “a Slang term for a “casual” gun owner; eg; a person who typically only owns guns for hunting or shotgun sports and does not truly believe in the true premise of the second amendment. These people also generally treat owners/users of so called “non sporting” firearms like handguns or semiautomatic rifles with unwarranted scorn or contempt.” recently sighted in some number in the latest post on open carry.

    Hey, Editoral staff might be interesting in one of your infrequent surveys, to collect a demographic of your readership. Would guess this website skews younger and more ethnically diverse than the OFWG stereotype.

    • Haha, a whole new chapter in my “book” (a collection of random life advice that involves a lot of firearms specific info): Internet slang for gun forums.

  13. Dear Anner, You did a pretty good job in hitting on a number of definitions and getting them largely right. Where you went egregiously wrong was in defining the function of a “primer”. A cartridge primer does not “detonate” the smokeless powder in the cartridge, the primer “ignites” the powder. There is an enormous difference between an ignition and a detonation, or a deflagration for that matter. When the primer is struck it ignites and sends hot particles and gasses through the touch hole of the cartridge into the main body of the cartridge to ignite the powder within. The powder does not detonate, it ignites, rapidly, but it doesn’t detonate. We’re talking orders of magnitude here. The ignition of a smokeless powder is measured on a scale of milliseconds, whereas a detonation of explosive material, on the other hand, is measured on a scale of microseconds or perhaps even nano seconds. Cartridges don’t detonate, they ignite.

    • This is seen dramatically when one piles up a bunch of smokeless powder and a bunch of black powder.

      The former, when ignited, just burns very quickly.

      The latter, with a large enough pile, will result in an explosion.

      Smokeless propellants don’t explode – they just burn very, very quickly, and their rate of burning goes up with pressure. The more smokeless powder in a cartridge, the higher the pressure – the higher the pressure, the faster it burns. The faster the burn, the higher the ultimate pressure… and round and round we go, until either we’ve burned up all the powder or something lets go on the gun.

      Perhaps another way to illustrate the difference: As a firefighter, I wouldn’t be all that apprehensive about going into a house or store where there’s a bunch of smokeless powder cans stacked up. Class A foam and water should tamp that fire down pretty well.

      Go into a building with cans of black powder piled up? Nope. No thanks, I’m going to be over “there,” behind something nice and solid.

  14. Most of those grizzled old guys have a lot more going on than outward appearances may suggest. Just saying. If you have a little humility around them it’s easy to learn new things.

    • No issue whatsoever sitting down to soak in the knowledge of older folks that care to share their experience. I’ve gleaned much of what I know from those encounters. I also appreciate those that share common errors, such as when the 4473 changed a few years back. I thought I was hot stuff filing that form out in record time, then I forgot to mark my ethnicity in the new column. I sit through the 10sec form walk through at shops I don’t regularly frequent, since they’re doing a good service for those that may only fill out a 4473 twice in their life.

      However, for every honestly selfless, good-hearted instructor of firearms knowledge, I’ve seen at least 1 arrogant prick. An older guy at a gunshop where I live now tried convincing another gentlemen that he was stupid for buying subsonic 22LR, since it wouldn’t cycle his 10/22. I didn’t say a word, but all I could think of was the thousands of subsonic 22LR I’ve had cycle through my various 10/22s. That’s one example, but it’s typical of “that guy”.

      The other day, I had a pleasant conversation with a gentleman that taught me more than I’d ever known about Damascus steel knives. I truly enjoyed that talk, and I intend to return for another. Maybe even buy one.

      Be the former, and avoid the latter.

  15. Much needed and well done. Except pistol. A revolver is a type of pistol, as is a single shot or a derringer. Even a flare gun or a flintlock can be called a pistol.

  16. Should add anatomy as well:
    Forcing cone,

  17. There were pistols long before there were semi-automatic firearms.


    a short firearm intended to be held and fired with one hand.
    verb (used with object), pistoled, pistoling or (especially British) pistolled, pistolling.
    to shoot with a pistol.

    Origin of pistol

    1560-70; < Middle French pistole < German, earlier pitschal, pitschole, petsole < Czech píšt’ala literally, pipe, fife, whistle (presumably a slang term for a type of light harquebus employed during the Hussite wars), akin to pištět to squeak, peep

  18. Great article! I learned several new things, always a pleasure.

    But gosh fellas… if we all actually agreed on every definition and term… what in the world would we talk about much of the time? LOL

  19. Technically it’s not .30 caliber. It’s 30 caliber without the decimal, or .30 without the word “caliber.” By definition, “caliber” is 0-point-something inches. A one caliber bore is 1 caliber, or 0.01″. A 100 caliber bore is 1″ in diameter. So “.30 caliber” would be 0.003″ or something.

    If you’re talking about a specific cartridge rather than bore size, it’s better to say chambering or (name) cartridge, such as .30-06 Springfield, not .30-06 caliber.

  20. Being one of those grizzled old guys, I run into a different problem mostly young guys behind the counter espousing that which they don’t have a clue, a little Background, Navy Veteran {VN}, Hand gun Instructor, State Hunter Safety Firearms instructor! Had a young clerk try telling me a Decocker on a Sig was a safety! but the best one was, buy this super duper pooper scooper scope and you’ll never miss again, {electronics were not as evolved nor as sophisticated as today} then I was talking to a young former sniper learned some good stuff from him! not too say that I haven’t had a few old guys try too BS Me when buying a Weapon, just goes to show their are Idiots on all sides of the time Line!


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