The most common shotgun gauges are 10, 12, 16, 20, 28, and .410. Note that .410 shotguns are actually .410 caliber, as the gauge of .410 shell would be roughly 67.
The smaller the gauge, the larger the diameter of the bore. 12 and 20 gauges are the most common - especially within the United States - and are both exceptionally powerful. It is also a good budget-minded choice. At stores like Walmart, a 100-round case of 12 or 20 gauge ammunition can be purchased for around $20.00, and these cases are quite abundant However for these prices one would be buying birdshot loads which would only be fatal to a classical zombie at extremely close ranges. (less than 30M). The same cannot be said for the other gauges, though lead bird shot is typically the least expensive.
Shotguns rarely have a large magazine capacity, generally between 4-8 shells in the magazine tube so reloading is frequent and usually slow. Another issues is that shotguns typically have more recoil. (depending on the type of ammunition and type of shotgun) The operation of a shotgun is also generally less user friendly depending on the action type. Shooters operating any manual type of shotgun, I.E. Pump, Lever, or Bolt action must ensure they fully cycle the weapon to avoid malfunctions. Operator error is the most common cause of malfunction for any tool, pump shotguns especially.
One advantage of the shotgun is stopping power. A full power Buckshot load for a 2 3/4" shell will have between 7-12 pellets of 00buck which will stay in a a group about the size of a pie plate for about 10-30 yards depending on the type of shotgun, the choke or lack of one, and its overall barrel length. Each pellet of 00 buck is roughly the size of a .32 caliber bullet.
Rifled slugs also will hit much harder then most full sized rifle calibers at close range. The energy of a 300 grain slug moving at 2000 Feet per second will be about 3623 Joules. By contrast a 125 Grain 7.62X39 round moving at 2365 Feet per second produces 2111 joules.
Break-action shotgunsPopularized by Mad Max and Western movies, break-action shotguns have hinged barrels, and are reloaded by opening the hinge and exposing the breech, allowing for used shells to be manually removed, or ejected out by a spring and unfired shells to be inserted. Break-action shotguns usually hold one or two rounds, corresponding with the number of barrels that are on the gun. These are arguably the simplest type of modern firearm design, and are likely to be fairly easy to find and are easily attained due to their popularity among hunters and sport shooters, however, double barrel shotguns tend to be more expensive then pump shotguns due to the level of craftsmanship. At time of editing this article, the lowest price on a used double barrel shotgun (side by side) on gunsamerica.com was $250 USD for a Syracuse foraging an gun co shotgun. The lowest price pump was a Mossberg 500 for $249 USD.
Break-action shotguns are simple and sturdy, but their low capacity of one or two shells and the lengthy process of reloading - though reloading can be expedited with training and practice- Break-action shotguns are usually as long as most full length rifles, making them excellent for medium range hunting, but this trait also makes them difficult to maneuver in tight spaces. Shotguns (particularly break-action shotguns) are sometimes modified by shortening the barrel and/or removing the stock, making the weapon significantly lighter and more compact, at the price of a shorter effective range, power, and accuracy. Another problem is that if you are shorting it yourself and you have no idea what your doing, you can easily ruin the gun. Such a shotgun is said to be "sawed-off", and if
shortened below a certain point, the legal term is "short-barreled shotgun" or SBS. In the US, this limit is 18" of barrel, and 26" in overall length. Due to the perceived popularity of such weapons with criminals in the past, this style of shotgun is either illegal or highly restricted in most jurisdictions.
Most break-action shotguns have their two barrels laid out side-by-side, but some have the two barrels one above the other. This is called an "over and under" shotgun, but occasionally referred to as an "over-under" or "O/U" shotgun. These are very popular with sports shot-gunners because they are very well-balanced, though professional shooters usually have the shotgun carefully fitted to them. "Over-under" shotguns can be very expensive - Browning and Beretta O/U can exceed $25000 USD.
A break action shotgun is a good choice as they are powerful, simple to operate and require little maintenance. However, the trade-off is the low shell capacity, at one or two shotgun shells. Another turnoff is that in the heat of fighting zombies with your adrenaline pumping you are more likely to fire both barrels, which may or may not kill the zombie. Forcing you to reload which is all it takes when fumbling around for another shell that the zombie bites you and kills you. So forth break action is not exactly the best choice, but not a bad one either; it beats throwing rocks any day of the week. If you find one, take it until you find a better weapon.
Break action shotguns are the slowest to reload shotgun of any modern shotgun, save a muzzle loading shotgun.
These shotguns work the same as bolt action rifles, they are just shotguns. They are usually found in .410 caliber, but they can be had in 20 and 12 gauge as well. If you have to choose one of these for the zombie apocalypse don't fret it, because it will be a great tool that you will be able to learn to operate quickly and easily. Bolt-action shotguns typically feed from very small magazines and are no more accurate than any other sort of shotgun.
A viable option for those who live in states (or countries) that don't allow pump-action or semi-automatic shotguns. Many of these shotguns are cheaper than their pump, or even break-action counterparts. If this is going to be your choice for the zombie apocalypse you have made a good one, but unless you have magazines that are higher than 2 or 3 rounds, please for your own sake find a higher capacity firearm. Always try to find a better firearm.
Lever-Action ShotgunsLever-action shotguns operate on the same principle as their lever-action rifle kin -- the operation of the weapon is performed by the "lever" that also constitutes the trigger guard. In North America, the popularity of "lever-action" shotguns is beginning to rise because of cowboy-action shoots.
Lever-Action shotguns are very similar to pump-action shotguns, in that a tube underneath the barrel holds the shells, and the lever operates the bolt, which when operated performs several tasks in conjunction. When opened, the bolt moves back in the receiver, the extractor of the bolt removes the shell inside of the chamber (unload), cocks the trigger and hammer, and strips an unfired shell out of the magazine tube, staging it to be loaded into the chamber. When the lever is lifted, closing it, the bolt slides forward, locking this unfired cartridge into the chamber, making the shotgun ready to fire. If the shooter squeezes the trigger, the hammer falls, firing the shotgun, and unlocks the action so that the cycle can be repeated. A Winchester Model 1887 in 12 gauge holds 5 shells in the magazine tube, though this depends largely on what gauge the shotgun is chambered for - .410 shotguns may occasionally hold more.
Pump-action shotguns have a single barrel, which is mounted above a tube magazine, into which shells are inserted. New shells are chambered by pulling the pump forearm attached to the tube magazine toward the user, then pushing it back into place to chamber the cartridge. This action simultaneously ejects the most recently fired shell out of the ejection port. Pump-action shotguns can be considered the most common, and affordable type of shotgun. They are often used by civilians for hunting, skeet shooting and home defense and can be fired as fast as the user can pump the slide and pull the trigger. Reloading is a fairly slow process, however, the shooter can load shells directly into action and chamber a new round as quickly as they can get the shell to the gun and move the pump forward. This allows the shooter to fire the gun as quickly as they can load it.
With practice the pump shotgun can have the potentially fastest reload from empty. In this video, Cowboy action shooter Spencer Hoglund (a.k.a Lead Dispenser) Fires 4 shells from empty, reloading between shots, in 2.87 seconds
Some strange custom models, such as the "Remington 1740", have two barrels and one stock. Another double barrel pump action shotgun is the DP 12. A double barrel, bullpup shotgun. Some pump shotguns are capable of slam fire, which is where the firing mechanism resets, and fires without taking ones finger off the trigger. This allows the shooter to fire the shotgun as fast as one can pump it, two notable models of shotguns capable of this are older Ithaca model 37's and the Winchester Model 1897.
A common shotgun is the Remington 870. It is reliable, available, inexpensive and popular. This allows availability of service and modifications.
The Mossberg 500 is another common shotgun. Its use of an aluminum receiver cuts weight with out sacrificing durability, can be had for about $250-$350 USD. Another great model is the Mossberg 590 and the 590A1 The differences respectively are that the 590 Uses an aluminum trigger guard, the barrel is attached differently, has metal parts in the safety, and a heavier barrel.