Introduction
The previous installments of this series covered various rifles. I wrote about the .22 Long Rifle, pistol-caliber carbines, hunting rifles, and semi-automatics already, but there is an entirely different class of long guns I need to discuss: shotguns.
Rifles are named for the spiral grooves inside the barrel which cause a bullet to spin and gyroscopically stabilize for long-range accuracy. Their predecessor was the musket, a muzzle-loading smooth-bore firearm used for hunting and military purposes alike. While the musket could certainly be loaded with small shot rather than a musket ball, fowling pieces were designed specifically for hunting game birds with shot, and the blunderbuss was a combat and self-defense weapon designed to use shot in close range.
Gauge
Welcome to the insanity of Imperial units of measurement! This one actually makes some sense historically, though. Gauge and bore measurements used to refer to how many properly-sized spherical bullets could be cast for that firearm. One pound of lead makes 12 balls fitting a 12-gauge, or 20 balls for a 20-gauge. Bigger numbers mean smaller bores.
12-gauge is the most popular in the US, with 20-gauge following behind. Either is suitable for self-defense or hunting, with the former offering more power, but the latter almost always still offering enough and then some.
If you are not in a country using leftover English colonial units, what alternate labels do you use for shotgun gauges?
Shot
While rifles are designed to shoot aerodynamic bullets at high velocity with long-range accuracy, shotguns are designed to fire a cluster of small pellets called shot. It is in the name, so I am sure this is not a huge surprise. The spread of the pattern also led to the nickname, "scattergun."
Shot can broadly be categorized into birdshot and buckshot, with various designations for the different sizes of shot available. In general, the larger the number, the smaller the shot pellets, similar to the shotgun gauge bore size. When shot larger than #1 is used, birdshot switches to letter designations, and buckshot uses and increasing number of zeroes. 00, or "double-aught" buckshot is a common defensive and military round. #8 birdshot is common for skeet and trap as well as smaller game birds, while #2 or BB birdshot might be used for geese and turkeys.
While shot has traditionally been made from lead, concerns about pollution and lead toxicity have resulted in a variety of steel and alloy alternatives, too. Since shotshells are typically identified in part by the total weight of the shot, lighter material may result in more pellets downrange with a proportionate loss in energy per pellet. The benefits and drawbacks of this tradeoff is an argument for another post, and I am not sure I am qualified to write it.
Because shot patterns spread after leaving the barrel, and each individual pellet has relatively little mass, range is limited. Instead of a cylinder bore simple tube, shotguns intended for waterfowl or other game often reduce the diameter of the barrel near the muzzle. This is called a choke, and there are several options. Some barrels are made with a specific choke profile, others have various threaded inserts for versatility. The narrowing at the muzzle reduces the rate at which the shot cluster spreads, maintaining better pattern density at longer ranges.
Slugs
Remember that bit about gauge, bore, and muzzle-loading muskets? Well, your old Remington Wingmaster can be a modernized rapid-fire musket, too. Most modern slugs are cast as a squat barrel shape instead of a sphere, and they usually have rifling spirals as part of the design to improve accuracy. It is not as good at long range as a rifle, but it adds versatility to a single weapon system, and can be sufficiently accurate in the woods even with basic shotgun bead sights. There are also options to swap to rifled slug barrels with more rifle-like sights for many popular models. That kind of versatility is a major benefit in a survival scenario.
Shotshells
Most shotgun shells consist of a brass base containing the primer pocket and powder charge, but transition to a polymer wall for most of the length. Above the powder, there is typically a wad separating the payload from the powder. This may be a simple plastic spacer or a complex shot cup designed to control the spread pattern. Finally, there is a slug or specific weight of shot pellets, and the front of the case is crimped closed to seal everything.
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Shot shell length is given before crimping, so a typical 2-3/4" 12-gauge shell is usually less than 2-1/2" long.
Powder is now smokeless, but shells are still often marked in dram equivalent to black powder. Consult a gunsmith before using modern smokeless powder cartridges in any antique firearms regardless of markings! If you are reloading your own shells, remember this means the smokeless equivalent of X drams of black powder, not X drams of smokeless powder. You do not want a kaboom. Consult your reloading manual!
Shot is defined by size and weight. A skeet and trap load might be 1 oz. of no. 7-1/2 birdshot, for example. Smaller pellets mean better pattern density, as do more pellets . Either more powder or more payload weight mean Mr. Isaac Newton's laws hit you in the shoulder harder. Remember the basic physics equations of F=m•a & E=m•a²?
Break action
The simplest commonly-available shotguns break open at the breech to eject and load shells. These many be just a single barrel, side-by-side double barrel "coach guns," over/under sporting guns, or various less-common configurations including combination guns with a rifle barrel and a shotgun barrel.
Over/under models in particular are popular with hunters and competition shooters in skeet and trap. These can be plain-jane utilitarian guns, or highly ornamented. I would suggest less bling in a survival scenario, but then again, an elegant hunting shotgun looks less like an "assault weapon" to the ban-happy hoplophobes. After all, grampa had one.
UPDATE: Forgotten Weapons has released a video about the Alofs conversion for single-barrel break-action shotguns. It was once possible to order a Rube Goldberg machine that bolted to your ultra-basic shotgun to give it repeater firepower... sorta-kinda.
Pump action
It you want a reliable repeater, you still probably went with a pump-action even in the mid-1920s when that gadget was released. These repeating shotguns are very popular among hunters, police, and the military due to the larger ammunition capacity and reliable mechanism. A slide under the barrel pulls shells from the magazine while cycling the bolt, and then an arm lifts the shell into position to feed into the chamber as the slide returns the bolt forward into battery.
In the USA, the Remington 870 is an iconic sporting gun, and the Mossberg 500 is a major rival, as is the Winchester 1200. Ithaca, Stevens, and other companies have made various competing designs, too. Additionally, if you watch many action movies, the SPAS-12 is probably familiar...
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Semi-auto
...But that SPAS-12 has a secret: It is not just pump-action. It can switch to cycle itself! It also has a gas system to fire as a semi-automatic. However, that complicated mechanism makes it a relatively heavy shotgun, and it is also expensive as a result. The SPAS-12 may be banned by name as an "assault weapon" in your jurisdiction because it looks scary and was designed as a military and police weapon.
Other gas-operated shotguns look much more traditional, and they still tap some of the expanding gas from the fired cartridge to operate what is essentially an internal pump action. Other mechanisms also exist, and while a straight blowback shotgun would be unpleasant at best, Benelli is known for the "inertia driven action" delayed-blowback mechanism with a very good reputation. Here is a video that lets you look inside both systems.
Others
Shotguns are available in many other configurations, including the perennial Call of Duty video game favorite, the lever-action Winchester 1887. Bolt action shotguns also exist, but these are far less common, at least in the US. Military armorers may have access to fully-automatic combat shotguns like the AA-12..
One more option to note: the relatively low pressure and large diameter of shotshells make pipe shotguns feasible. These usually have a short pipe fitted with a fixed firing pin inside a capped breech at one end, and fitting into the other end is another removable smaller-diameter pipe as the barrel which is loaded, inserted, slammed back into the firing pin to fire the shell, and then disassembled for cleaning/reloading. While these are usually associated with clandestine and improvised arms manufacturing, there was apparently at least one commercial release of this pattern.
Now, I am not recommending using scrap pipe and leftover lumber to take advantage of any government gun "buyback" schemes, but do with this information what you will.
Concluding Thoughts
Shotguns offer extreme versatility. Birdshot is suitable for waterfowl and rabbits. Buckshot is good for self-defense, and potentially shooting deer as the name implies. Slugs are even better for deer, and offer a measure of precision at range. Ammunition is fairly easy to come by, at least where I live, especially in 12- and 20-gauge. Of particular interest to preppers, shotshells can be reloaded with relative ease if you have powder, primers, wads, and your preferred projectiles. You need proper tools and a press, of course. I am not particularly familiar with the process, but my dad used to do this when I was little.
Since you can select anything from a simple single-barrel break-action to a fully kitted-out combat-ready pump action or autoloader, you are spoiled for choice when it comes to finding what you want. Simple shotguns are low on the priority list for ban-happy congresscritters, if that is of concern. For survival, I would probably recommend an inertia system if you want a self-loader. It is lighter, it can better handle adverse conditions and infrequent maintenance due to its design.
Downsides exist, though. Shotguns are LOUD. Ammunition is bulky and heavy if you expect to be on the move. Recoil, while not severe with target loads, can be stout with heavy turkey or goose loads, slugs, and buckshot.
On a personal note, I participated in the skeet & trap club at the community college I attended for drafting and design. I used a plain-jane Mossberg 500 12-gauge with an 18" cylinder bore barrel for skeet, and I just swapped to a longer modified choke barrel for trap. I was not very good, but that was not the gun's fault. Blasting clay pigeons is a good way to familiarize yourself with real-world shotgun handling, and it is a heck of a lot of fun.
