Rifles primer

Rifles

    History of the Rifle
    Types of Rifles
       Bolt Action
       Lever Action
       Slide or Pump Action
       Semi-automatic Rifles
          Blowback Action
          Recoil-operated
          Gas-operated

History of the Rifle

It is thought that the technique of applying spiral grooves to the inside bore of a barrel we call “rifling” began to appear in the late fifteenth and early sixteenth centuries. Oral tradition claims rifling first evolved from the straight cuts in a bore made in 1498 by Viennese marksman Caspar Kollner to facilitate loading. The earliest written description of a spiral rifled firearm is found in an inventory of firearms from Turin, Italy, dated 1478.

The 19th century saw perhaps the greatest rate of invention in the evolution of the rifle. It opened with the Napoleonic Wars where massed formations of troops confronted each other with single-shot, muzzle loading flintlocks and ended with the world’s armies equipped with sophisticated repeating rifles that fired fixed, metallic ammunition. With the transition from ignition systems of scraps of sharpened flint sparking against steel frizzens to percussion cap ignitions (similar to today’s primers), firearms technology began moving at a rapid pace.

The American Civil War was the first major war where rifled firearms were employed by troops other than special units. The increased accuracy and distance gained by rifling the barrel’s bore also made it one of history’s bloodiest wars. During that terrible half decade, military small arms technology began to favor breech-loading weapons where powder, primer and bullet were contained in a single brass cartridge case.

During the last four decades of the 19th Century, manufacturers such as Sharps, Maynard, Remington, and Whitney produced popular and accurate single-shot rifles that fired metallic cartridges loaded via the firearm’s breech. Others, such as Winchester, Marlin, and Ballard, concentrated on lever-action rifles.

In Germany, the Mauser family was developing the bolt-action rifle, while Britain, in keeping with the demands of big-game hunting, concentrated on single and double barrel rifles capable of withstanding powerful cartridges.


Types of Rifles
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Modern rifles come in all types, including working reproductions of cowboy-era rifles. There are “slide-action” rifles that operate identically to their slide or pump action shotgun cousins, as well as lever actions, bolt actions, and semi-automatic actions.

Bolt Action Rifles

Germany’s Paul Mauser is credited with inventing the first successful metallic cartridge bolt-action rifle in 1867. The bolt-operated firearm has a low, cylindrical receiver that cradles the bolt. The bolt’s handle projects over the receiver wall to the right (except in actions built specifically for left-handed shooters), pointing either in a straight line from the bolt itself, or curved downward towards the trigger guard. The two principal types of bolt actions are the turn-bolt and the straight-pull.

In the turn-bolt design, lifting the bolt handle rotates the locking lugs on the bolt out of engagement and begins the cartridge extraction process. Pulling the bolt handle to the rear extracts and ejects the fired cartridge case. Pushing the bolt handle forward strips a fresh cartridge from the magazine toward the chamber. Turning the bolt handle down engages the locking lugs in the corresponding recesses in the receiver and locks the action preparatory to firing.

Turn-bolt actions for high-power cartridges always have two or more locking lugs to reinforce the receiver’s strength. For rifles chambered for low powered .22 rimfire cartridges, a locking lug may not be present on the bolt. Instead, some manufacturers use the square surface of the bolt handle that locks into a special cut in the receiver as the locking mechanism. Others, particularly high-quality competitive rifles, use the locking lug technique.

In a straight-pull action, pulling the bolt straight backward unlocks the action and, with the same movement, extracts and ejects whatever is in the chamber. Pushing the bolt straight forward reloads the empty chamber and locks the action.

The Mauser-derived turn-bolt action has a system of cam-cocking that causes the firing pin to be pulled back into the bolt’s body and away from the primer when the bolt is lifted and moved rearward. When the bolt handle is turned down, the camming motion completes the compression of the main spring and cocks the rifle.


Lever Action Rifles
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As its name indicates, the characteristic feature of a lever action rifle is the lever located below the receiver. The lever also forms the trigger guard.

The lever action rifle’s breechblock, an oblong steel block carrying the extractor and firing pin, is locked and unlocked by the action of the operating lever. Working the lever down and forward opens the action. Returning it to its original position with an upward and rearward swing closes the action. Lever guns do not use lugs to lock the breechblock into place. Instead, some have breech locks that wedge between the face of the breech and the receiver’s rear wall. Others have locking bolts that are raised into locking grooves in the side walls of the receiver.

Lever guns can have an exposed hammer or hammerless design. They may have tubular, box, or rotary magazines.

Slide or Pump Action Rifles

Most, but not all, slide-action rifles are made to fire the .22 rimfire. Tubular magazines are most commonly found on slide-action guns.

Slide action rifles are sturdy and simple to operate. The rifle’s operating rod or “action bar” runs from the fore-end or “slide handle” under the barrel through a slot in the receiver to the breechblock. A stud on the rear end of the action bar rides in a camming slot in the side of the breechblock. When the slide handle is pulled to the rear, the action bar lug is forced backward in its slot in the breechblock and the sloping slot cams the breechblock either up or down depending on the make of the rifle. The locking lug is disengaged from its seat in the receiver. The continuation of the rearward pull causes the unlocked breechblock to extract and eject the fired cartridge case, cock the rifle, and raise a new round from the magazine.

Pushing the slide handle forward pulls the breechblock forward and pushes the new cartridge off the carrier into the chamber. The lug on the action bar comes up against the camming section of its slot and cams the locking lug into its recess in the receiver completing the chambering of the round and locking the breech into position prior to firing.


Semi-automatic Actions
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The three main categories of semi-automatic rifles are blowbackrecoil operated, and gas operated. These are the same categories found in semi-automatic handguns and shotguns.

 
Blowback Action RiflesThe blowback action is the simplest. It is a popular action for .22 rim fire cartridges. The blowback action consists of a relatively heavy breechblock that freely moves back and forth in the receiver. Gases released upon firing force the head of the cartridge case up against the face of the breechblock. The breechblock is then driven forward by the recoil or operating spring.While simple in concept, the smooth operation of this type action depends upon just the right mix of applied physics and mechanical functioning. When a cartridge is fired the resultant gases not only push the bullet up the bore towards the target, they also exert sideways pressure on the walls of the cartridge case and rearward pressure that forces the head of the cartridge case against the breechblock.Factors to be considered are the weight of the parts needed to be moved, friction, and the power necessary to compress the recoil spring. If a rifle is to operate smoothly, all mechanical parts must perform their roles flawlessly. To achieve that desired status and mechanical/ballistic harmony, the parts, spring tension, etc. must all be ideally suited to the particular type ammunition you will be shooting. When all factors are in proper balance, the effect of the gases on the breechblock will cause the breechblock to be sent on its rearward journey after the bullet has exited the bore and the sideways pressure forcing the cartridge case tightly against the receiver walls has subsided.In order to avoid constant problems, the rifle’s breechblock must not be so heavy that it fails to move after a round is fired. In this case, the action will jam because of the failure to cycle through the firing, extracting and ejecting, reloading process. The reverse situation is equally undesirable: namely, the breechblock moves so rapidly that the extractor tears off the head of the cartridge, rather than removing the entire case from the chamber.Delayed or Retarded Blowbacks use a variety of devices to prevent the breech from opening as rapidly as in a straight blowback gun.
 
Recoil Action RiflesIn recoil action rifles, the barrel and the breechblock actually slide in horizontal guides for a short distance while locked together when the gun is fired. The rearward motion of the barrel halts when it engages a stop in the receiver. The extremely short time it takes until this point allows the pressure in the chamber to drop sufficiently where the cartridge case is no longer pushed violently against the chamber walls and is now extractible.Once the barrel’s motion is halted, a cam unlocks the breechblock from the barrel, allowing it to continue traveling to the rear, during which time it extracts and ejects the cartridge case, cocks the hammer, and compresses the recoil spring. At the end of the breechblock’s rearward movement, the recoil spring drives it forward to load a new cartridge and cam its locking surfaces into their seats in the barrel.
 
Gas Operated RiflesIn gas-operated actions, a small amount of gas is bled off into an auxiliary chamber, where it pushes a piston that creates a force to unlock and open the action. The action is closed and locked by a recoil spring that is compressed during the rearward action. Gas-operating systems can use a long-stroke piston or a short-stroke piston.The long-stroke design siphons off gas under somewhat low pressure via a port near the muzzle. The operating rod is fastened to the piston stem and extends all the way back to the receiver where it engages the breechblock or bolt. The short-stroke design takes its charge of high-pressure gas by means of a port only inches forward of the chamber. The operating rod is not attached to the piston stem; rather, it is mounted just behind it. The piston is driven violently to the rear where it hits the forward end of the operating rod. This blow drives the operating rod to the rear causing the same process of unlocking, extracting, ejecting, cocking, reloading, and locking as occurs in the long-stroke design.

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