The last few years have seen a sharp rise in internet queries asking "What are the two basic styles of firearms actions?" and "How is a single shot firearm different from a repeating firearm?"

Such questions reflect a broader curiosity about firearm mechanics among gun enthusiasts, collectors, hunters, and anyone who might be unfamiliar with the fascinating evolution of arms development. As the world's number one auction house for fine and historic firearms, Rock Island Auction Company is uniquely positioned to present some of the rarest and earliest examples of gun action types to the collecting public.

Most of the examples featured here can be frequently found at Rock Island Auction Company. Click on the images to learn more about each model.

An extremely rare prototype Swingle & Huntington Model 1874 lever action rifle, as featured on the Cover of "The Gun Report" November 1962 issue.

How is a Single-Shot Firearm Different From a Repeating Firearm?

The question of what are the two basic styles of firearms actions is really an inquiry into how we define an action and how we define a repeater.

For an answer to the latter question, Merriam-Webster describes a repeater as "a firearm having a magazine that holds a number of cartridges loaded one at a time into the chamber by the action of the piece."

A repeating and a single shot firearm. (Top) A Remington-Lee bolt action rifle. (Bottom) A Sharps Model 1874 Buffalo rifle.

So what exactly is an action? One common definition classifies the action as "the part of a firearm that loads, fires, and ejects a cartridge." This is somewhat correct, and certainly applies to many modern firearms, but a more layman's definition might describe the action as the main mechanical component of a firearm that includes the firing mechanism and often a means to load and eject the cartridges. Break actions are manually loaded and in many cases have an extractor rather than an ejector, for example.

That said, perhaps a more encompassing definition for a repeater would be a firearm with a cycling action that's supplied mechanically from an ammunition feeding device, be it a magazine, revolver cylinder, belt, or tube. A single shot firearm does not have an ammunition feed.

From lever guns to revolvers, the mid 19th century saw an explosion of repeating arms development.

Single Shot Actions

Early gunmakers experimented with numerous ways to achieve multiple shots, including designs like the Kalthoff and Cookston repeater, the Belton fusil, and the Ellis Jennings sliding lock. These models were expensive and time-consuming to produce, and were less suited to the elements compared to the single shot muzzleloader.

Find antique single shot firearms of every era at Rock Island Auction Company.

Single shot breechloaders were explored in the 17th and 18th centuries in an effort to reduce reload time, with examples like the Ferguson rifle screwed breechblock demonstrating the technology during the Revolutionary War. Advances in metallurgy and manufacturing techniques made the single shot breechloader a more viable platform, with the Model 1819 Hall rifle becoming the first breechloader to be regularly adopted by the U.S. military.

An exceptional U.S. Harpers Ferry Model 1819 Hall breechloading flintlock rifle dated 1838.

Falling Block Single Shot Actions

While the Hall rifle's tilt up breech block action was an impressive design, the platform suffered from similar gas leakage issues that had plagued prior breechloading models. Christian Sharps' 1848 patent offered a substantial improvement with its "sliding breech-pin" (breechblock) action. By pressing the lever down and forward, the breechblock lowered to allow the shooter to load into the breech end of the barrel. When the lever was pulled backward and up, the breechblock moved upwards to seal the breech.

Though initial Sharps models were designed for powder and ball, the platform proved well-suited for chambering metallic cartridges of the 1860s. The general style of the Sharps action, and numerous popular single shot models to follow, fall into the "falling block" or "dropping block" style of action. Historic examples include the Marlin-Ballard, the Gibbs, and the Peabody.

A Sharps Model 1874 heavy barrel buffalo rifle available, a popular example of a falling breechblock single shot action.

Hinged Breechblock Single Shot Actions

Where falling block actions operate by opening and closing the chamber through the vertical movement of a solid breechblock, a hinged breechblock employs a pivoting mechanism to achieve the same goal for a single shot action. Historic examples include the Civil War Joslyn rifle, the English Snider, and the French Tabatiere. Perhaps the most prolific hinged breechblock design was developed by Erskine S. Allin in the form of the Springfield Trapdoor, a cost-effective way to convert tens of thousands of surplus muzzleloaders into cartridge breechloaders.

A U.S. Springfield Officer's Model 1875 Trapdoor rifle.

Rolling Block Single Shot Actions

The rolling block, another common single shot action, employs a breechblock that pivots on a horizontal pin. The user cocks the hammer, exposing the chamber for loading before rolling back into place. Remington was the action's most prolific producer, with their Rolling Block rifle becoming the most widely used single shot military breechloader of the 19th century.

A Model 1902 Remington rolling block, one of the most sucessful firearm action types in history. This model features improvements over the Model 1897 before it, including a rotary extractor and a side-swept breech block lever.

Break Action Single Shots

Break action, or "tip-up" firearms like the Stevens and Maynards are one of the most prolific gun action types for single shot rifles, pistols, and shotguns. The break action rifle has long been employed as a reliable truck gun, varmint gun, and a training option for young shooters to cut their teeth. Today, this sturdy gun action can be found in models like the T/C Contender series, the H&R Handi-Rifle, the Henry single shot,  the Rossi Wizard, the Savage 24, and almost any side-by-side or O/U shotgun.

A Stevens No. 41 pistol, one of four Stevens tip up single action firearms in the lot that demonstrate the versatility of this early 20th century design.

Bolt Action Single Shots

The bolt action platform originated as a single shot system. In the 20th century, bolt action single shots were produced as military training rifles, and .22 models like the Winchester Model 02 served as common target and varmint shooting models. Many modern bolt action single shot options are available today, ranging from the diminutive .22 Cricket, the mighty AR-50 in .50 BMG, to heavy hitters like the 14.5 and .700 JDJ pictured below.

A McMillan Bros. bolt action rifle in 14.5 JDJ (left) and an MMCI bolt action rifle in .700 JDJ (right).

The Revolver

Inventors who dabbled with repeating firearms explored numerous gun action types throughout the centuries, and the revolver is one of the oldest repeating designs. Dating back to the 16th century, early matchlock revolvers used manually revolving chambers. These weapons were costly to produce and suffered from reliability issues, but gunmakers continued to experiment with the design as metallurgy improved and new ignition systems became available. Perhaps the Colt revolver's most famous successor was produced by Elisha Haydon Collier from 1818 to 1827.

An engraved E.H. Collier percussion revolving shotgun.

Samuel Colt was the first to realize the concept of accurately syncing a rotating cylinder to a fixed barrel, laying the foundation of nearly every revolver to follow. The Colt Paterson and Walker led to some of the most famous single action black powder percussion revolvers of the 19th century. Cartridge revolvers like the Smith & Wesson No. 1 and the Colt Single Action Army made reloading faster than ever and became some of the most preferred sidearms in the frontier era.

Two of the earliest Colt revolvers: a Paterson (left) and a Colt Walker (right.)

With a single action revolver, the action must be manually cocked and pulling the trigger fires the weapon. In a double action system, both functions are accomplished simultaneously by pulling the trigger. The double action revolver was popularized in Europe with the invention of the Adams patent, and by the late 19th century America had embraced the design as well. Today, countless single action and double action models are available, though DA/SA revolvers that offer both functions dominate the market.

A Colt Python double action revolver.

The Lever Action

One of the most famous types of actions to rise in the 19th century was the lever gun. The July 29, 1848 issue of the 'Saturday Morning Visitor', a paper in Warsaw, Missouri, praised a new firearm that Lewis Jennings had patented, noting the gun was, "a repeating rifle, capable of discharging forty balls a minute," where each charge could be "brought to its place by moving a slide with the fore finger, which can be done in an instant."

This slide referred to a lever used to move back the bolt and lift new cartridges from the magazine into the chamber. The Jennings, which drew off earlier patents from Water Hunt's Volution Repeater, laid the foundation for numerous successors like the Volcanic, Henry, and early Winchester lever action rifles.

A Volcanic Repeating Arms Company No.2 lever action Navy pistol.

Among numerous improvements, the Henry rifle introduced an ejector system, firing pins independent from the bolt face, and the ability to chamber a metallic rimfire round. The Spencer rifle offered similar innovations, and both weapons demonstrated the effectiveness of these new types of actions on the Civil War battlefield.

The first Winchester rifle, the Model 1866, improved loading speed with the "King's gate," the steel framed Model 1873 offered a sturdier centerfire chambering, and the sized-up Model 1876 provided even more firepower. Competitors like Marlin introduced models capable of chambering some of the most powerful hunting rounds of the era, and Winchester would soon follow suit. The Winchester 1887 and 1901 would lay the blueprint for the lever action shotgun.

A Winchester Model 1887 lever action shotgun.

The lever gun remains one of the most popular types of actions today, though typically in a sporting or target shooting role using flat or round nose bullets loaded into a tubular magazine. Firearms like the Winchester Model 1895 and Savage Model 1895 demonstrated the versatility of the lever action, with the Winchester employing a box magazine and the Savage designed around a stack magazine, each capable of chambering pointed rounds.

Perhaps the most unexpected influence of the lever action is exhibited by John Moses Browning's M1895 "Potato Digger" machine gun, where a gas-actuated loading lever is used to cycle the belt-fed action.

A Russian contract Winchester Model 1895 lever action musket.

Bolt Action

Numerous repeating types of actions were developed in the 19th century, including the bolt action system. The majority of bolt actions operate by pushing a round into the chamber, rotating to lock the breech, and ejecting spent casings by pulling up and back.

Invented by Johann Nicolaus von Dreyse in 1824, the bolt action started as a single shot platform. Bolt action repeaters with tubular magazines like the Kropatschek, Vetterli, and Lebel rifles emerged, and models like the Remington-Lee 1885 introduced the box magazine, an ideal system for working with the high-pressure Spitzer bullets that would later emerge in the smokeless era.

A scarce U.S. Navy contract Remington-Lee Model 1885 bolt action magazine rifle with U.S.S. Philadelphia marking.

Several variations emerged as the bolt action system developed, including the straight pull design. Compared to the four-step operation most turn bolts required to load, a straight pull bolt action offered a two step process. Models like the Steyr Mannlicher, Swiss 1896, and Canadian Ross rifle were adopted as military arms, their turn bolt competitors proved more durable and affordable. In 1993, Blaser introduced a modernized version of the straight pull bolt action to the sporting market, which led to numerous new designs from Blaser and its competitors.

A Blaser R8 Professional in 7mm Remington Magnum. The Model R8 straight-pull bolt is regarded by many Blazer fans as one of the most reliable rifle actions available.

Today, repeating bolt action rifles can chamber nearly every common sporting or military rifle cartridge, from .220 Swift to titans like the .600 Overkill. Though their reign as standard issue military arms was surpassed decades ago by semiautomatic and automatic models, bolt actions continue to serve in specialized sniper roles.

This American Hunting Rifle by Wayne Jacobson, built on a CZ 550 action, is chambered in .600 Overkill.

The Slide Action

Today, the pump shotgun is one of the most common types of actions for the scattergun platform. This action involves sliding a forend back to eject a cartridge, which also cocks the firearm in most systems. The forend is slid forward to load a new round. More officially called the slide action, the first successful commercial variation of the system was introduced in 1882 by the Spencer Arms Co.

An exhibition quality, factory engraved Spencer slide action shotgun.

The slide action was adopted for a variety of shotguns and rifles in the late 19th century. Between 1884 and 1904, for example, Colt produced more than 185,000 Colt Lightning slide action rifles. The Winchester Model 1890 rifle saw nearly 850,000 units produced, and models from Remington, Marlin, and Mossberg also found impressive success.

The slide action became one of the most prolific gun action types for shotguns. The Winchester Model 1897 popularized features like an easy to remove barrel and magazine tube that have become industry standard, and platforms like the Winchester Model 12 and Ithaca Model 37 further improved the concept. Today, the Remington 870 and Mossberg 500 have each surpassed 11 million units produced and continue to serve in a wide variety of roles.

A Colt large frame Express Lightning slide action rifle in .40-60-260 caliber.

Most slide action shotguns employ tube magazines, though models like the Mossberg 590M, SPAS 15, and Iron Horse Sentry 12 are fed from box mags. Though slightly slower than their semiautomatic counterparts, slide action shotguns can run lighter loads since they aren't dependent on gas to cycle. Hybrid models have been produced that offer both options, like the famous SPAS 12.

The SPAS 12 offered a dual mode that allowed its users to choose either a manual pump action or gas operated semiautomatic action at the touch of a button.

Autoloading

In terms of subcategories, autoloading includes the greatest number of different gun action types. An autoloading action broadly refers to any firearm system that automatically chambers a new round after each shot. Hiram Maxim set the stage in 1884 with his recoil operated machine gun, and numerous types of gun actions that offered automatic and semiautomatic capabilities were introduced over the next two decades.

Blowback

A blowback action harnesses the force of the cartridge's expanding gases to propel the bolt rearward, clearing a spent casing and cycling a fresh round into the chamber.

The simple blowback action found in many submachine guns that use comparatively low pressure rounds operates purely on bolt weight and spring resistance to manage timing. The most basic autoloading action type, this system is sometimes called "pure" or "straight" blowback.

A Smith & Wesson Model 76.

In a roller-delayed blowback action, the bolt carrier features side-mounted rollers that create mechanical resistance, slowing the bolt’s rearward travel after firing. This system eliminates the need for gas tubes, ports, or pistols, enabling lighter and mechanically simpler weapons. Popular models like the H&K G3 and MP5 utilize this reliable action type.

A scarce factory original G3 selective fire rifle sold for $26,438 in RIAC's December 2024 Premier Auction.

The gas-delayed blowback system uses the gas generated by firing to delay the action from cycling until the bullet exits the muzzle and the pressure drops. This offers lighter recoil to the shooter and improved accuracy, but the system is limited to lower pressure rounds and can result in more rapid overheating. Examples that use this type of gun action include the H&K P7, the Steyr GB, and the Walther CCP.

A German Heckler & Koch P7 semiautomatic pistol.

A toggle-delayed system is a gun action type that employs a mechanism in the bolt assembly that locks the breech until chamber pleasure drops, ensuring safe and controlled cycling. Early guns like the Luger and Maxim used the toggle in conjunction with a short recoil system, and John Pedersen fully embraced the design as a delayed blowback action in his Pedersen selfloading rifle.

This extremely rare Pedersen "T" series test carbine sold for $37,457 in RIAC's September 2021 Premier Auction.

Another of the many different gun actions John Pedersen experimented with, the hesitation lock uses a separate locking mechanism to briefly delay the bolt, allowing smoother cycling. In addition to the SIG MKMO submachine gun, Pedersen's Remington Model 51 pistol is the most famous example of this operating system and is one of the inventor's most successful designs.

A Remington Model 51 pistol in .380 ACP.

One of the rarest types of gun actions, a lever-delay blowback adds a fulcrum in order to delay the speed of the bolt unlocking from the chamber. Examples that employ this system include the French FAMAS and AAT-52, the Hungarian Kiraly 39M and 43M SMG, and the Italian FNAB-43 submachine gun.

The French FAMAS is an example of a lever delayed blowback action. This French MAS St. Etienne "MAS 223" FAMAS semiautomatic bullpup rifle sold for $49,938 in RIAC's May 2024 Premier Auction.

Blow Forward

Another one of the lesser known gun action types, the gas pressure in a blow forward system is employed to drag the barrel ahead instead of backward, accelerating in the same direction as the bullet. Not surprisingly, this system results in greater recoil. Only a few notable designs were built around a blow forward action, including the Mannlicher 1894, the Hino-Komuro 1908, and the Schwarzlose 1908.

A Schwarzlose Model 1908 blow forward pistol.

Recoil

One of the most common gun action types, recoil operated systems rely on the energy of recoil to cycle the action instead of gas pressure. For more than a century, short recoil has been used by most semiautomatic handguns chambered for high pressure rounds, from early efforts like the C93, C96 Broomhandle, and Colt 1911, to modern day Glocks. In short recoil systems, the barrel and bolt recoil together only briefly before disengaging, differing from their long recoil counterparts.

Two early short recoil operated pistols. A Mauser 1896 20-shot flatside cone hammer broomhandle pistol (left) and a Ludwig Loewe Model 1893 Borchard pistol (right).

Several early shotguns like the Browning Auto-5 and the Winchester 1911 utilize a long recoil action that pushes the barrel and bolt back when fired, ejecting the cartridge. The bolt separates from the barrel only after completing a full cycle, pulling a shell from the magazine into the chamber to reload the gun. Other collecting rarities built for this action include the Chauchat machine gun, the Frommer Stop, and the Mars Automatic pistol.

A Belgian Browning Auto-5 Light Twelve semiautomatic shotgun.

Unlike traditional recoil actions, inertia-operated systems like the Swedish Sjögren utilize a locking block linked to the firing pin to delay bolt movement. By the time the bolt begins cycling, chamber pressure has safely dissipated, allowing smooth extraction and reloading. This unique gun action type is used today in numerous successful Benelli shotguns like the M1 Super 90, the M2, and the Franchi Affinity series.

A Swedish Sjogren semiautomatic takedown shotgun manufactured in the early 20th century.

Gas Operated

Gas operated gun actions power their cycling sequence by redirecting the energy from a fired cartridge to unlock the bolt, eject spent casings, chamber a new round, and reset the firing mechanism. Numerous firearms were produced using gas-operated systems in the 19th century, though this gun action type truly came into its own in the years leading up to WW2.

One of Hiram Maxim's early patents was for a gas trap system, and John Browning used a variation in his M1895 machine gun. The gas trap action captured escaping gas at the muzzle to generate forward motion instead of gas from the barrel. Early German G41s and M1 Garands used this action, and both examples are highly sought after collector guns today.

A historic U.S. Springfield Armory T1E2 M1 Garand, serial number 5, as Photographed in Billy Pyle's "The Gas Trap Garand." Available this May.

John Garand ultimately opted to use a long-stroke gas system for his famous rifle. In a long-stroke action, the piston is linked to the bolt carrier through the length of the cycle. Some of the most popular guns of the 20th century use this robust system, including the SKS, the AK-47, the FN MAG, and early examples of the FN FAL.

A WW2 U.S. Springfield Armory M1 Garand semiautomatic rifle, manufactured in September 1942.

In contrast to long-stroke gas actions, the piston in a short-stroke system travels less than the distance of the bolt carrier, resulting in fast cycling and less felt recoil. The M1 Carbine and Soviet SVT-38/SVT-40 helped popularize this action type, and it serves as the operating system for countless modern rifles today.

"1941" Dated Soviet Podolsk Arsenal SVT-40 semiautomatic rifle.

Finally, we have direct gas impingement, which has a somewhat contentious definition. In the original volume of author Blake Steven's 'The Black Rifle M16 Retrospective,' he writes that "Stoner’s gas system utilized a simple open pipe, a concept first used in the Swedish Ljungman Gevär 42, and the later French 1944 and 1949 MAS semiautomatic rifles. In these relatively rudimentary applications, the gas piston and spring of a conventional gas-impingement system were replaced by the jet of hot gas itself, which traveled back through the hollow gas tube and impinged directly onto the face of the bolt carrier."

Eugene Stoner himself, however, differentiated his system from direct gas impingement. In his August 14, 1956 patent, Eugene Stoner wrote, "This invention is a true expanding gas system instead of the conventional impinging gas system. By utilization of a metered amount of gas from the barrel, the automatic rifle mechanism is less sensitive to different firing pressures caused by variations in the propelling charge."

A Swedish Carl Gustaf Ljungman AG-42 semiautomatic rifle with a 1943 dated receiver.

Rare Firearm Action Types at Rock Island Auction Company

So how is a single shot firearm different from a repeating firearm? Hopefully we've clearly illustrated the difference between a repeater with a mechanical action that cycles and feeds rounds from a magazine, cylinder, belt, or tube verses a single-shot firearm that lacks an integrated feeding system.

A Ken Owen "Owen-Rewa" 4 bore double rifle with a classic break open action.

At it's heart, the question of what are the two basic styles of firearms actions is really an inquiry into what separates a repeater from a single shot system, and how many broad gun action types are out there. The common answer is there are 6 types of firearm actions: the break open action, the revolving action, the lever action, the bolt action, the slide (or pump) action, and the semiautomatic action.

While our extensive list covers a lot of ground, there are countless subcategories, untested patents, experimental prototypes, and limited production rarities within many of these categories, as well as seldom-seen actions we didn't touch on, like the chain gun and rotary cannon. For gun collectors, history enthusiasts, and fans of unique engineering, you'll find the rarest of the rare at Rock Island Auction Company.

Find different gun actions from across the decades at Rock Island Auction Company, like these three rare James Merrill breech loading alterations.