Let’s Talk Shotguns

By John Gilstrap

Let’s say you’ve got a character in your story who had no background in firearms, yet needs to engage an armed bad guy.  A shotgun may be your character’s best choice, especially at close quarters.  Because every pull of the trigger sends multiple high-velocity projectiles downrange simultaneously, marksmanship is less of an issue when it comes to killing the enemy, but more of an issue when it comes to shooting only the enemy.

In previous posts, I’ve talked about rifles and pistols, so this week, I thought I’d devote some time to shotguns.  As a first step, forget much of what you’ve learned about rifles and pistols.  The rules of Newtonian physics all remain the same, but much of the terminology seems counter-intuitive when you deal with smooth-bore weapons.

Okay, what’s a smooth-bore weapon?

Whereas modern rifles and pistols fire bullets, shotguns fire either pellets or slugs.  As a bullet is propelled down a rifle’s barrel, the lands and grooves that have been cut into the metal to form “rifling” impart a spin on the projectile that stabilizes it in flight and allows for greater range and accuracy.  Standard shotguns, on the other hand, have no rifling down the bore.  The barrel is simply a smooth tube.  (Note: there is such a thing as a rifled shotgun, but I won’t be addressing that here.)  Basically, a smooth-bore barrel is merely an extended pressure vessel that allows the projectile(s) to accelerate.

Think gauge, not caliber.  Think spheres, not bullet-shaped.

It’s common to refer to rifles and pistols by the diameter of the bullets they fire.  A “.30 caliber” rifle fires a bullet that is three-tenths (.30) of an inch in diameter at its widest point.  A “.45” fires a bullet that is 45/100ths of an inch at its widest point.

Shotguns, on the other hand, are referred to by their “gauge” and the term has nothing to do with linear measurement.  To understand the reason why, we need to geek out a little:

One characteristic of elemental lead is that when melted, its physical volume is a constant, relative to it’s weight.  Thus, a one-pound sphere of lead will always be 1.66 inches in diameter (assuming I did the math correctly).  From the days of the Napoleonic Wars through the American Civil War and beyond, one of the primary artillery cannons was the “twelve-pounder”, which, predictably, I suppose, fired a twelve-pound ball (also called a “shot”–as in the shot put event in track-and-field, get it?) out of a barrel that was 4.62 inches in diameter.

The concept of “gauge” is based on the same principle, but in this case dealing with fractions of a pound.  The bore of a 12 gauge shotgun is the diameter of a lead sphere that weighs 1/12 of a pound, or 0.727 inches.  A 20 gauge shotgun has a bore of 0.617 inches, which is the diameter of a lead sphere that weighs 1/20 of a pound.

Still with me?

One of the most counter-intuitive parts of discussing shotguns is the fact that unlike calibers, higher gauges actually mean smaller projectiles.

Buckshot, Birdshot, Slugs.

So, we’ve got our smooth-bore shotgun of a chosen gauge–for our  purposes here, we’ll assume 12 gauge if only because it the most common shotgun deployed by law enforcement officers.  The size of the bore is largely just a reference point; it has little to do with the weight of the projectile being sent downrange.

One of the strengths of a shotgun as a weapon platform is its versatility.  The same gun can be used to hunt doves and deer, and then when you come home, it can be a great home defense weapon.  Different applications require different ammunition, though, and here’s where things get complicated again.

Starting with the basics, each round of ammunition is called a “shell”, not a “bullet” or a “cartridge”, as would be case with rifle and pistol ammo.  Inside the shell, the pellets (or “shot”) are separated from the propellant (or “powder”) by a plastic cup that is call the “wad.”  Each pull of the trigger sends a “load of shot” or a “slug” downrange.  Once spent, the “hull” is ejected.

When the load reaches the muzzle on its way downrange, the pellets are tightly grouped together, but as they travel through the air, they separate to form a spray of projectiles.  The width of the spread and the terminal performance of individual projectiles has everything to do with their size and their weight.  “Birdshot” refers to smaller, lighter pellets that are designed to kill smaller, lighter prey.  “Buckshot”, on the other hand, is designed for larger prey.  Within, say, 10 feet, both are equally lethal.

Here again, smaller is bigger.  The size of individual pellets is described by industry-accepted numbers.  On paper, you might read “#4 buck”, but you would pronounce it as “number four buck.”  And #4 buck is smaller than #3 buck.

What most people think of when they’re talking about buckshot is #00 buck, which is commonly referred to as “double aught buck.”  (Note: It’s NOT double ought.)  Individual pellets are 0.33 inches in diameter (.33 caliber) and there are nine of them in an ounce.  By contrast, #4 buck pellets are 0.24 inches in diameter (24 caliber) and there are 24 of them in an ounce.

Bird shot is also categorized by numbers, but on a different scale.  For example, No. 4 bird shot pellets are 0.13 inches in diameter, and there are 135 of them in an ounce.

A slug is a single projectile that essentially turns the shotgun into a less accurate rifle and hits with enormous force.  Slugs come in many different forms and perform many different functions.  For example, when you hear of riots being dispersed by the use of “rubber bullets”, those “bullets” are really rubber slugs, or sometimes beanbag slugs.

Types of Shotguns.  

Double barrel shotguns have been around for a very long time, back to the days of the flintlock.  The classic arrangement for the barrels was “side-by-side”, as characterized by bird hunters and stage coach security guys.  You know that’s where the phrase “riding shotgun” originated, right?

The second configuration of a double-barrel shotgun is the “over and under” configuration, where the barrels are stacked.  As a bit of trivia, you’ll note that there’s only one trigger on the gun.  The act of closing the breech cocks the gun.  The lower barrel shoots first and the recoil re-cocks the gun so the top barrel will fire.

Semi-automatic.  As with its rifle counterpart, you can load the magazine to whatever its capacity may be, and every pull of the trigger sends a new load downrange until the magazine is empty.

Pump-action.  This is the mainstay of cop shows and sound effects crews.  Also called a “shucker”, this configuration requires the shooter to work the pump to eject one hull and put the next shell into battery.

So, there you have it, TKZers, this quarter’s offering of gun porn.  All questions, comments and observations are welcome.


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About John Gilstrap

John Gilstrap is the New York Times bestselling author of Lethal Game, Blue Fire, Stealth Attack, Crimson Phoenix, Hellfire, Total Mayhem, Scorpion Strike, Final Target, Friendly Fire, Nick of Time, Against All Enemies, End Game, Soft Targets, High Treason, Damage Control, Threat Warning, Hostage Zero, No Mercy, Nathan’s Run, At All Costs, Even Steven, Scott Free and Six Minutes to Freedom. Four of his books have been purchased or optioned for the Big Screen. In addition, John has written four screenplays for Hollywood, adapting the works of Nelson DeMille, Norman McLean and Thomas Harris. A frequent speaker at literary events, John also teaches seminars on suspense writing techniques at a wide variety of venues, from local libraries to The Smithsonian Institution. Outside of his writing life, John is a renowned safety expert with extensive knowledge of explosives, weapons systems, hazardous materials, and fire behavior. John lives in the Eastern Panhandle of West Virginia.

23 thoughts on “Let’s Talk Shotguns

  1. Talk a little about the shooter’s perspective, John. All shotguns have a “kick” to them, and some more than others. Plus, it takes some training (and bruises?) to get used to that. And they’re freaking loud, too.

    So in a book if a slender character who is new to guns grabs the family shotgun to fend off an intruder, there should be several recoil consequences, right?

    • Good questions, Jim. And as is so often the case, the answer is . . . It depends. A 20 gauge shotgun is easily wielded and shot by children. It’s sort of a starter bird gun. The smallest gauge for a shotgun is actually a .410 (it’s the only shotgun measured as a caliber–and I don’t know why), and its recoil is very manageable–but its lethal range is very limited.

      When you get to the more standard 12 gauge, assuming standard loads, recoil is certainly noticeable, but still not terrible–a fraction of what you’d get from a deer rifle, for example, and a small fraction of the boom you’d get from pretty much any rifle intended for game larger than a rabbit.

      Remember that force (or recoil) equals mass (the weight of the projectile(s) multiplied by acceleration (feet per second, squared–sorry I don’t know how to do superscript on this platform). In general terms, as projectiles get heavier and powder loads get larger, recoil increases, and the lighter the weapon, the greater the “felt recoil.”

  2. Your first point on accuracy is nicely shown in John Wayne’s El Dorado where James Caan fires his sawed off monster into a crowd of bad guys—and also hits the good guy Wayne. Oops.

  3. I’ve seen your gun porn presentations, and they’re fascinating, but make my head hurt. I’m a stickler for accuracy, but know my limits. Hence, in my newest release, I wrote it like this:

    “As bad scenarios went, this one could be worse. Cole went to his trunk for his shotgun. When a suspect has a gun, go in with a bigger gun.”

  4. Ahh…this was an entertaining post! I know stuff about guns, but I sure didn’t know all of this-thanks!

    I used to work in law enforcement (not on the line), and I also used to shoot high powered rifles and a trusty Colt Python .357 magnum in competition. Those were some heady days. When I worked in LE, I was one of those lucky ducks who had to qualify twice a year on the shooting range and the pursuit driving range. I loved it all.

    My current WIP has two shooters: a .44 magnum revolver, and a .450 Marlin, both owned by my mountain man protag. A large male cinnamon bear is intimately introduced to the .44.

    Thanks for an informative post. Always learn something here. 🙂

    • Ohhh, a Python! I envy you that! I loved my time in LE too. Two careers I’ve loved, how lucky am I?

      Never had to qualify on driving, but my husband taught defensive and offensive driving to the California Highway Patrol back in the day, so I figure I learned what I needed to anyway. 😉

  5. Wonderful refresher, John. Thank you. You always explain technical issues clearly.

    In the early nineties, we went shooting at the venerable Homestead resort in Hot Springs, VA, with a friend who was a member. The members were a well-heeled lot with their Barbour jackets and fancy Bennelli shotguns. Husband set me up with my dad’s old 12 gauge Mossberg with the 18″ barrel attached. Plus, I was 6 months pregnant. Did we get some stares! Husband has a very twisted sense of humor.

    • He sounds like a guy I’d like.

      One thing that pisses me off at a range, and that you don’t see very often anymore, is the boyfriend/husband who takes his inexperienced other out to shoot far more gun than they’re prepared to handle. With proper stance, grip and eye relief, there will be no bruises and everyone will have a much better time.

      When I take out a new shooter, there’s always as minimum one hour “ground school” on all the basics, with a huge emphasis on safety. In fact, when I have a student, my eyes never leave their gun.

  6. My husband would love this post. He is a walking encyclopedia of guns, all types. I felt bad for him when we first married. I was not familiar with guns since my dad never hunted and I didn’t know a rifle from a shotgun. You can bet I do now!

    In fact, I had the ultimate gun experience when my husband took me on an African Safari. We were at two different hunting concessions in Zimbabwe. The first just across the river from Kruger National park in the Crooks’ Corner of South Africa, Mozambique, and Zimbabwe. He used a .375 H & H for buffalo and leopard, kudu, and impala. He let me use his 270 Winchester. I fired two shots and got to trophies, wart hog and a nice impala buck.

    I have yet to shoot one of his shotguns, but I have shot his 45 ACP and the 9 mm Smith and Wesson Model 39. 😀 (And yes, he coached me on how to write all this.) Needless to say, he keeps my writing straight, along with police procedures since he is a retried police officer and well as a gentleman’s hunter.

    Which reminds me about a shotgun story. A man was visiting an prestigious English gunmaker in England and commented that the 12 gauge side by side shotgun he was examining was stiff to break open. The salesman gave him a disapproving look and said, “Sir, our clients to do not open their guns. The loader does that for him.”
    (And yes, I was coached on this too.)

    I enjoy your posts, even though some of the detail makes my eyes roll, just as when me husband starts in about grains, velocity, and on an on. But, through that, I glean what I need to make my stories plausible. 🙂

    Thank you for another interesting and informative post.

  7. Shotguns have an enormous intimidation factor. Like you mentioned, Mr. Gilstrap, the pump action type especially.

    We had a US Marine Detachment (MarDet) on my ship (USS Saratoga) and when the security alert alarm sounded they’d come running down the passageways with their pump-action shotguns. It didn’t matter who you were, from lowly airman to XO, when you saw them coming with their guns, you made like a bulkhead (wall) and didn’t move a muscle until they were past. Pretty much everywhere on a ship, with the exception of the flight deck and hangar bay is close quarters. I suppose that’s why they used the shotguns.

    (For security alerts, there were no drills – it was always a real threat…. Until it was called finished, then the marines would be notified if it were a drill).

    • Hi Carl — there was also a marine detachment on board the guided missile cruiser (I can neither confirm nor deny the presence of nuclear weapons on board) USS Albany. “Gunsmoke!” sounded over the 1MC any time an onboard space security breach occurred or just for a drill — we were never informed which was which. The biggest marine in the detachment was maybe 6’4” and big like a tight end. One time, when I was plastered back-to-bulkhead, this guy ran toward me carrying his 9 in one hand and the clip in the other, per procedure. and came to a watertight hatch opening.

      As he ran up to it he kinda scrunched up, ducked his head, and landed a foot onto the bottom of the opening to propel himself through and on down the passage, like you do. But he also accidentally simultaneously pushed up, and conked his noggin on the top of the hatch.

      He went down, out cold, and his piece and clip hit the linoleum tile on the deck and both skidded quite a ways. A couple of minutes went by before the drill was secured and the marine CO and ship’s medics came and tended to the marine. Sailors in the corridor handed the CO all the weaponry.

      The story later was that one round was missing from the clip when he checked the 9 in later that day, and he was busted later at a marine mast. If so, somebody in that corridor had to have either picked it up while it rolled loose, or pulled it out of the mag. Or it was just a bullshit story. The marines never talked much about their business, and unlike our Captains Mast results the marines never published punishments.

      • “I can neither confirm nor deny the presence of nuclear weapons on board” 🙂 Brings back some memories.

      • Not to push any unnecessary buttons, but I respectfully offer a couple of gentle corrections. The part of the weapon that is inserted into the grip of a pistol or the underside of the action on a rifle is a magazine, not a clip. I was a Marine (always capitalized) for 21 years in the FMF (Fleet Marine Force). I never served on board a ship as part of a Marine detachment, but I suspect the story you heard was BS. Had the Marine been brought up on charges under the UCMJ (Uniform Code of Military Justice), he’d have gone to a Captain’s Mast like anyone else on the ship.

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