Shotgun Action Types
By Chuck Hawks
The seven steps of operation of any firearm (rifle, shotgun, or pistol) are the same. The purpose of the action (mechanism) of any gun is to perform these seven steps. All actions accomplish the following steps of operation either mechanically or by hand, although not necessarily in this order:
1. FIRING--pulling the trigger releases the hammer or striker and fires the shell in the chamber.
2. UNLOCKING & PRIMARY EXTRACTION--the breech is securely locked closed during firing; after firing, the first operation is to unlock it. Autoloaders do this by means of gas pressure and an operating rod, other actions do this by manual movement of a bolt handle, slide handle, etc. In addition, the case left behind after the shot charge, wad, and powder are gone must be loosened from the chamber walls--this is called primary extraction, and it is accomplished mechanically as the action is unlocked.
3. EXTRACTION--the case is partially or fully removed from the chamber.
4. EJECTION--after extraction the case is removed from the gun; it is either lifted out by hand or thrown out by the ejector.
5. COCKING--The hammer or striker spring is compressed as the hammer/striker is drawn back, and then held back by the sear; it is now cocked.
6. FEEDING--a fresh cartridge is chambered, either by hand, or by the forward travel of the breech-block (bolt).
7. LOCKING--The breech-block is locked closed, and the gun is ready to fire again.
Specifically how these seven steps of operation are accomplished, and in what order, depends upon the type of action. I am not going to attempt to detail how each action accomplishes these steps; it is sufficient to understand that it does. If you carefully watch a shotgun mechanism operate, you will see how it performs the seven steps.
The shotgun actions I am going to cover in this article are the autoloading action, the pump action, and the break action (single shot and double barrel). These are the action types that the vast majority of modern shotguns employ. I will try to briefly point out the advantages and disadvantages of each type, and mention some of the best known shotguns that employ each type of action.
There are other shotgun types that I will not touch on here, such as the unusual Darne sliding block action or the inexpensive bolt action. But these types represent only a small percentage of shotgun sales. The latter works like a bolt action rifle--see my article The Bolt Action in the "Rifle Information" section of my Guns & Shooting Page for more information.
Long recoil operated, short recoil operated, and gas operated autoloading actions were all devised by John Browning, and the firm that bears his name has made all three types. The most famous long recoil action is the Browning Auto-5. This same design has been produced by Remington (as the famous Model 11), Savage, and others. All of these guns can be easily recognized by the familiar "square back" receiver.
A long recoil action uses the force of recoil to achieve the seven steps of operation. It requires the barrel and bolt (locked together) to travel rearward for a distance somewhat greater than the full length of the fired cartridge before coming to a stop so that the fired shell may be extracted and ejected. Then the barrel unlocks from the bolt and returns to battery, followed a little later by the bolt, which strips a fresh shell from the magazine and chambers it as it returns to battery. Springs, compressed on the rearward movement, power the return to battery of the barrel and bolt. The jolt caused by the heavy barrel/bolt assembly reaching the end of its rearward travel immediately after the recoil caused by the firing of the cartridge gives the long recoil gun a peculiar "double shuffle" kick, which some shooters find disconcerting.
The short recoil shotgun also uses recoil energy for power, but the barrel and bolt are only locked together for a short distance, usually less than 1/2 inch. Then the two are separated and the barrel returned to battery by a spring while the bolt continues rearward to eject the fired case. At the end of its travel the bolt is forced forward (by another spring) and it strips a fresh round from the magazine and chambers it as it returns to battery.
The Browning Double Automatic was an interesting example of a short recoil operated shotgun. Most autoloading pistols also operate on the short recoil principle, and this is where the system has found its most common application.
The gas operated autoloading shotgun uses the power of the expanding gas from the power charge to operate the action. It works in a similar manner to the gas operated autoloading rifle, so for a more detailed description of this action I will simply refer you to my article The Autoloading Action in the "Rifle Information" section of my Guns & Shooting Page.
Probably the best-known gas operated shotgun ever made, and typical of the type, is the Remington Model 1100. This benchmark design has influenced the great majority of subsequent autoloaders. It has proven to be a reliable gun that significantly reduces perceived recoil. As I write this in 2007 the 1100 is still in production. Gas operated autoloaders are offered by most manufacturers of repeating shotguns.
Autoloaders are very popular for the various clay target sports and also for hunting. They offer reduced perceived recoil (about 30%, due to the energy absorbed in operating their action) and a quick, almost effortless, second or third shot. This reduced recoil is particularly advantageous for trap and skeet shooters, who may shoot hundreds of rounds a day. It is also pretty important to the waterfowl hunter shooting magnum loads.
Autoloaders are a little more expensive than an equivalent pump gun, but much cheaper to manufacture and sell than a decent double gun. The shooter wishing to increase the versatility of his or her autoloader can purchase a second barrel of different configuration at a reasonable price. Barrels can usually be interchanged in minutes without tools. Today, at least in North America, autoloaders are probably the best selling type of shotgun.
Autoloaders generally require more maintenance than other types. Without it they are apt to become less reliable than a manually operated action, particularly in very cold weather. They must be kept clean and should be inspected for proper adjustment and worn parts on a regular basis. Other shotgun types will run practically forever if you merely swab out the chamber and bore and wipe down the outside of the gun with a silicone cloth. This is not true of autoloaders, and particularly gas operated autoloaders.
The primary disadvantage of the autoloading shotgun, besides increased maintenance, relates to the length of the receiver necessary to contain its action. This long receiver between the barrel and butt stock makes an autoloader about 4" longer than a break action gun with the same length barrel. Autos tend to be muzzle heavy and slow to swing with a barrel longer than 26" in length. This is a disadvantage shared with the pump gun (see below).
Some shooters find the automatic operation of the action between shots distracting, especially when shooting clay target doubles. Some autos tend to be fussy about ammunition; they will often fail to eject light loads, and sometimes fail to feed heavy loads.
Reloaders dislike the fact that autos throw the fired shell on the ground. Some autoloaders also tend to be sensitive to reloads, and will only operate with reloaded shells previously fired in their chamber. This can be a pain in the neck for the reloader that owns more than one shotgun.
Most experienced shooters consider autoloaders the most dangerous type of shotgun in the hands of a careless or ignorant shooter. Because, after the first shot, it is ready to shoot again with no action required by the shooter beyond pulling the trigger. This is, of course, also true for a double gun with a single trigger. Safety is really an operator problem, as the autoloader is as safe as any other repeater when used correctly. Careless individuals are dangerous to themselves and others with any sort of gun, and also around motor vehicles, boats, aircraft, power tools, matches, propane stoves and lanterns, machinery of all kinds, and electricity. They should be studiously avoided.
The pump action is cycled by "pumping" the forearm after a shot is fired. The forearm is connected to the breech-bolt by rods called "action bars." These cause the bolt to move with the forearm, performing the seven steps of operation. There are two motions to pumping a shotgun. First the forearm is pulled straight to the rear. This initially unlocks the bolt, then extracts and ejects the fired shell as the bolt moves rearward. When the forearm reaches the end of its rearward stroke, it is pushed in the opposite direction, straight forward. It pulls the bolt with it, until the bolt once again locks in the fully forward position. During its forward motion the bolt picks up a fresh shell from the magazine, pushes it into the chamber, and locks into place. The gun is then ready for another shot.
The best selling pump gun in history is the Remington Model 870, and the most famous is probably the Winchester Model 12. Winchester introduced the Model 1300 pump gun in 1964 as a replacement for the Model 12, and has produced it ever since. The 1300 was designed to be less expensive to manufacture than the classic Model 12. In recent years Browning has built a very nice pump gun named the BPS. These guns, along with the Mossberg 500 and its descendants, typify the American pump gun. In North America the pump was the most popular type of shotgun for a good part of the 20th century. Today, the autoloader has relegated the pump to second place, but the pump gun is still a strong seller.
Pump guns handle virtually identically to gas operated autoloaders. Because of their long receiver they tend to be muzzle heavy if equipped with a barrel the same length as typically found on a break action gun. A pump gun with a 24" barrel is about the same overall length as a double with 28" barrels, and handles well, but the short barrel increases muzzle blast. A 26" barrel gives a pump about the same overall length as a double with a 30" barrel. Repeaters like pumps and autoloaders usually handle best with 26" barrels, and a 28" barrel is a practical maximum for field use. A pump with a 30" barrel is about the same length as a double with a 34" barrel, which is pretty clumsy for most purposes.
Because of its relatively low price, reliability and multi-shot capacity the pump action shotgun has for many years been a favorite of both the military and the police when a short range, hard hitting weapon is called for. Short barreled "riot gun" type pumps have also become popular with urban residents, who may indeed be faced with a riot just beyond their front door, started on the flimsiest of pretexts.
The principal advantages of the pump gun are its relatively economical price, 3+ shot capacity, reliability and fast manually operated action. Although it is not as popular in competition as the over/under or autoloader, many trap and skeet shooters do use pump guns and a quick second shot for doubles can be achieved with practice. Reloaders who favor repeaters like pump guns because a fired shell can be ejected into the hand rather than onto the ground.
Pumps are particularly useful as field guns. They are not sensitive to ammunition and can be used with light or heavy loads, including reloads. A second barrel (longer or shorter) or multiple choke tubes can be purchased to increase the versatility of the gun at modest cost. A pump gun is usually the cheapest, and often the best, way for the occasional shotgun shooter to get into a repeater that is suitable for fast follow-up shots in the field.
The break action
Break action shotguns commonly come in single barrel and double barrel styles. Single barrel guns are usually either inexpensive beginner guns or special purpose trap (competition) guns. Double barrel guns have the barrels placed side-by-side or one superposed over the other (over/under). There are also a few three-barrel break action guns called "drillings." They usually have two side-by-side shotgun barrels over a single rifle barrel. Never very numerous, drillings have generally been made in Europe (especially Germany and Austria), but back around the turn of the 20th Century there was a Three Barrel Gun Company in the U.S. that made drillings.
Any break action gun is the safest of all shotgun types, since simply opening the action reveals whether it is loaded and renders it inoperable. It also makes it very easy to check for barrel obstructions. A break-action gun should not be closed until it is time to shoot.
The single barrel, break action shotgun is compact, light, handy, well balanced and effective. It is most commonly seen as a beginner's field gun. These are usually rather plain, inexpensive, mass produced guns stocked in hardwood or plastic, but seldom walnut. They often have an external, rebounding hammer that must be cocked before they can be fired. If equipped with an ejector a single barrel can be reloaded fairly rapidly.
The H&R Topper line of single barrel shotguns is typical of the breed, and perhaps the best known of the type today. Toppers are made in standard and youth sizes, and in 12, 16, 20, 28, and .410 gauges. A Deluxe model, in 12 gauge only, is available with screw-in chokes. There are also survival and deer hunter (slug gun) styles. New England Arms and Rossi also offer similar guns. In years past Sears, Western Auto, Montgomery Ward's and similar mass retailers sold about a zillion single barrel shotguns under various trade names. At one time Beretta, Winchester, Ithaca, Stevens and other well known manufacturers also built inexpensive single barrel shotguns. These were the shotguns with which generations of young Americans learned to shoot.
Another commonly encountered form of single barrel shotgun is the single barrel trap gun. These are top-flight competition guns, built by many of the famous double gun manufacturers. They are usually impeccably fitted and finished guns, typically featuring long 32 or 34 inch barrels with elevated ventilated ribs, beavertail fore-ends, and straight, Monte Carlo, or adjustable combs. The Browning BT-99 is perhaps the most famous of the breed, along with the legendary Ithaca Single Barrel Trap Gun.
Side-by-Side double barrel
The queen of shotguns is the elegant break action, side-by-side double barrel. No other design is as graceful or as aesthetically pleasing. Double guns are generally built on actions called "boxlock" (where the action parts--the locks--are carried inside of the action body), or "sidelock" (where the lockwork is attached to sideplates inletted into the wood behind the body of the action). Both types were invented in Britain.
World famous gun makers like Westley Richards, W. & C. Scott, Holland & Holland, Boss, Greener and Purdey largely brought the modern hammerless side-by-side double gun to perfection in Britain in the latter part of the 19th century. These British gun makers worked out the design of and set the standards for double guns. Many of them are still building guns today. Very fine double guns (often called "best guns") are also made in the U.S., Italy, Spain, Germany, Belgium, France and perhaps other places. See my article Best Shotguns for more information about these exquisite doubles.
Virtually all double-barreled shotguns today are of the familiar break-open design, fundamentally similar to the break-action single shot guns with which most kids learn how to shoot. To open the action, a top lever (operating what is called a Scott spindle) is pressed to the side and the barrels pivot down around a hinge pin at the front of the action bar, opening the action and exposing the breech end of the barrels for loading or unloading.
Most of the better double guns have automatic ejectors, which eject fired shell cases when the action is opened, but merely extract unfired cases from the chamber for easy hand removal. Automatic ejectors were developed to reduce the time it takes to reload a double gun, for while reloading must be accomplished by hand, unloading can be made automatic.
Competition guns usually forgo this feature, since two shots are the limit in competition and fast reloading is unnecessary. Also, most competitive shooters are handloaders and they do not like to have their empty cases thrown on the ground.
To speed reloading even further some doubles feature assisted opening. This uses some form of spring action to help kick the barrels open when the top lever is operated. Of course, this spring must be compressed when the gun is closed, requiring more effort to close the gun.
Another feature incorporated into most British best guns is the "clean" breech face. This is also intended to speed reloading, by eliminating any projections from the face of the breech that could interfere with the removal or insertion of shells. Unlike most American doubles, which hold the action closed by means of some sort of bolt through an extension of the top rib, British (also Spanish and Italian) guns typically use underbolts. These operate in a large central slot in the center of the action's watertable and lock into "bites" (deep notches) cut into "lumps" (lugs) placed centrally between the "flats" (underside) of the twin barrels, which fit into the slot in the action's watertable when it is closed. The Winchester Model 21, Ruger Gold Label and Savage/Fox Model B American doubles use the British system and have a clean breech face.
Hand detachable locks are often seen on certain British and Spanish best grade sidelocks. This feature permits the shooter to remove the sideplates with their attendant mechanisms for easy cleaning without resorting to tools. The interior of such locks are usually highly polished or engine turned, and sometimes the parts are gold plated. This seems like a very classy feature to me.
Some double guns also have a single selective trigger (SST), which the user can set to fire either barrel first and which then automatically resets to fire the second barrel. This is a complicated type of trigger. Not all makers of best guns offer a SST and some of those that do probably shouldn't. Many are prone to "doubling" (firing both barrels at once) or "balking" (not firing the second barrel when the trigger is pulled). Most British and Spanish SST's have a bad reputation and the famous American Parker shotgun's SST was among the worst. I have found the Browning, SKB and Winchester SST's to be very reliable. The single trigger used in the old (and new) A. H. Fox guns also had a good reputation.
There are also single non-selective triggers, which always fire the same barrel first. Since they are much simpler than SST's these usually work fine. Lots of fine European live pigeon (competition) guns come with non-selective single triggers because the open choked barrel is always fired first and a single trigger is perhaps a hair faster than double triggers. The deluxe version of the Savage/Fox Model B double came with a non-selective single trigger.
Most double guns intended for hunting still have two separate triggers, one for each barrel. Two triggers are perhaps the easiest way for the hunter to select which barrel to fire first. This design is the simplest, most reliable and gives the shooter, in effect, two entirely separate actions so that a malfunction in one does not render the other inoperable. Most of the powerful double rifles chambered for big bore cartridges, guns designed for the largest and most dangerous game, are built with two triggers for exactly this reason.
As you can perhaps tell, much thought and mechanical ingenuity has gone into the evolution of the double gun. In fact, a best grade double is the most highly evolved of all firearms. It is also the only common action type that has no military application. The modern double gun is strictly a civilian innovation.
A side-by-side double gun offers an instant choice of two chokes, short overall length (compared to a repeater) for any given barrel length, a trim receiver for easy carrying, a very quick second shot, superior "between the hands" balance and generally the best handling available in a shotgun. It is also the most graceful of all guns. As noted above, any break action gun is the safest of all shotgun types, since simply opening the action reveals whether it is loaded and renders it inoperable. The typical double's sliding tang-mounted safety is quicker and easier to operate than the safety mounted in the trigger guard of most repeaters. A double is also extremely easy to check for barrel obstructions.
Over/Under double barrel
Like side-by-side double guns, O/U actions can be of either the boxlock or sidelock type. The redoubtable John Browning popularized the O/U in the 20th century with his innovative Superposed boxlock design. The company that bears his name is still one of the largest suppliers of the type. Other very well known gun companies offering Over/Under shotguns include Ruger, Savage, Remginton, and Beretta. Pietro Beretta of Italy, the oldest gunmaker in the world, builds both boxlock and sidelock O/U guns. Perazzi, also of Italy, is especially well known for their O/U competition models, as are Kreighoff of Germany and Kemen of Spain. Boss, Holland & Holland, and Purdey of London, England offer exquisite sidelock O/U game guns in addition to their famous side-by-side models. David McKay Brown of Glasgow, Scotland makes a superlative over/under as well as a "round action" side-by-side.
In the last 50 years, more titles and trophies in trap and skeet, including Olympic medals, have been won with O/U guns than with any other type. Despite its somewhat ungainly appearance (compared to a side-by-side), the O/U is the best selling double barreled gun in the world today. The stack barrel can be made to balance and swing just as well as a side-by-side, but its receiver is thicker so it doesn't look or feel quite as trim.
The O/U's advantages include a single sighting plane, short overall length, excellent balance, tang-mounted safety and the same safety advantages as other break action guns. Most O/U's today come with single triggers and offer a very fast second shot, faster than an autoloader since no time is wasted while the action cycles. The first of these advantages is why most shooters today prefer it to the side-by-side. The other advantages are why so many top-level competition shooters prefer the O/U to repeating shotguns, despite its much higher price.
About the only disadvantage to any quality double, whether side-by-side or over/under, is price. These superior guns are expensive to manufacture.