Breech loading

  Breech loading

Main article: Breech-loading weapon

Loading mechanism of the Chassepot.

       From 1836, breech-loading rifles were introduced with the Gerrman Dreyse Needle gun, and followed by the French Tabatière in 1864 and the British Snider-Enfield. Primitive chamber-locking mechanisms were soon replaced by bolt-action mechanisms, examplified by the Chassepot in 1866. Breech loading was to have a major impact on warfare, as breech-loading rifles can be fired at a rate many times higher than muzzle loaded rifles and significantly can be loaded from a prone rather than standing position. Firing prone (i.e., lying down) is more accurate than firing from a standing position, while a prone rifleman presents a much smaller target than a standing soldier. The higher accuracy and range, combined with reduced vulnerability generally benefited the defence while while making the traditional battle between lines of standing and volleying infantry men obsolete.

Cartridge storage
       An important area of development was the way that cartridges were stored and used in the weapon. The Spencer repeating rifle was a breech-loading manually operated lever action rifle, that was adopted by the United States. Over 20,000 were used during the American Civil War. It marked the first adoption of a removable magazine-fed infantry rifle by any country. The design was completed by Christopher Spencer in 1860.[citation needed] It used copper rimfire cartridges stored in a removable seven round tube magazine, enabling the rounds to be fired one after another. When the magazine was empty, it could be exchanged for another.

20th century

     World War I and World War II had significant impacts on the design and use of the rifle. By the time of the first world war, the rifle had already been established as the stock weapon for modern infantry.

     Until the early 20th century rifles tended to be very long; an 1890 Martini-Henry was almost 2 m (6 ft) in length with a fixed bayonet. The demand for more compact weapons for cavalrymen led to the carbine, or shortened rifle.

     The advent of massed, rapid firepower and of the machine gun and the rifled artillery piece was so quick as to outstrip the development of any way to attack a trench defended by riflemen and machine gunners. The carnage of World War I was perhaps the greatest vindication and vilification of the rifle as a military weapon.

     Experience in World War I led German military researchers to conclude that long-range aimed fire was less significant at typical battle ranges of 300 m. As mechanisms became smaller, lighter and more reliable, semi-automatic rifles, including the M1 Garand, appeared. World War II saw the first mass-fielding of such rifles, which culminated in the Sturmgewehr 44, the first assault rifle and one of the most significant developments of 20th century small-arms. 

     During and after World War II it became accepted that most infantry engagements occur at ranges of less than 300 m; the range and power of the large battle rifles was "overkill"; and the weapons were heavier than the ideal. This led to Germany's development of the 7.92 x 33 mm Kurz (short) round, the Karabiner 98, the MKb-42, and ultimately, the assault rifle. Today, an infantryman's rifle is optimised for ranges of 300 m or less, and soldiers are trained to deliver individual rounds or bursts of fire within these distances. The United States Marine Corps, however, continues to train all of its riflemen to accurately engage targets out to 500m. Typically, the application of accurate, long-range fire is the domain of the sniper in warfare, and of enthusiastic target shooters in peacetime. The modern sniper rifle is usually capable of accuracy better than 0.3 mrad at 100 yards (1 arcminute).

Modern hunting rifle.

     By contrast, civilian rifle design has not significantly advanced since the early part of the 20th century. Modern hunting rifles have fiberglass and carbon fiber stocks and more advanced recoil pads, but are fundamentally the same as infantry rifles from 1910. Many modern sniper rifles can trace their ancestry back for well over a century, and the Russian 7.62 x 54 mm cartridge, as used in the front-line Dragunov Sniper Rifle (SVD), dates from 1891.

Technical aspects

Rifling
Main article: Rifling

     Some early rifled guns were created with special barrels that had a twisted polygonal shape, in particular the Whitworth rifle was the first to be made with the intention of spinning the round for the use of as a "rifle". Specially made bullets were designed to match the shape so the bullet would grip the rifle bore and take a spin that way. These were generally limited to large caliber weapons and the ammunition still did not fit tightly in the barrel. Many experimental designs used different shapes and degrees of spiraling; one widely produced example was the Metford rifling in the Pattern 1888 Lee-Metford service rifle. Although uncommon, polygonal rifling is still used in some weapons today with one example being the Glock line of pistols (which fire standard bullets). Unfortunately, many early attempts resulted in dangerous backfiring, which could lead to destruction of the weapon and serious injury to the person firing.

Barrel wear

     As the bullet enters the barrel, it inserts itself into the rifling, a process that gradually wears down the barrel, and also causes the barrel to heat up more rapidly. Therefore, some machine-guns are equipped with quick-change barrels that can be swapped every few thousand rounds, or in earlier designs, were water-cooled. Unlike older carbon steel barrels, which were limited to around 1,000 shots before the extreme heat caused accuracy to fade, modern stainless steel barrels for target rifles are much more resistant to wear, allowing many thousands of rounds to be fired before accuracy drops. (Many shotguns and small arms have chrome-lined barrels to reduce wear and enhance corrosion resistance. This is rare on rifles designed for extreme accuracy, as the plating process is difficult and liable to reduce the affect of the rifling.) Modern ammunition has a hardened lead core with a softer outer cladding or jacket, typically of an alloy of copper and nickel - cupro-nickel. Some ammunition is even coated with molybdenum-disulfide to further reduce internal friction - the so-called 'moly-coated' bullet.

Rate of fire
Main article: Rate of fire

     Rifles were initially single-shot, muzzle-loading weapons. During the 18th century, breech-loading weapons were designed, which allowed the rifleman to reload while under cover, but defects in manufacturing and the difficulty in forming a reliable gas-tight seal prevented widespread adoption. During the 19th century, multi-shot repeating rifles using lever, pump or linear bolt actions became standard, further increasing the rate of fire and minimizing the fuss involved in loading a firearm. The problem of proper seal creation had been solved with the use of brass cartridge cases, which expanded in an elastic fashion at the point of firing and effectively sealed the breech while the pressure remained high, then relaxed back enough to allow for easy removal. By the end of the 19th century, the leading bolt-action design was that of Paul Mauser, whose action—wedded to a reliable design possessing a five-shot magazine—became a world standard through two world wars and beyond. The Mauser rifle was paralleled by Britain's ten-shot Lee-Enfield and America's 1903 Springfield Rifle models (the latter pictured above). The American M1903 closely copied Mauser's original design.

 Range

     Barrel rifling dramatically increased the range and accuracy of the musket. Indeed, throughout its development, the rifle's history has been marked by increases in range and accuracy. From the Minié rifle and beyond, the rifle has become ever more potent at long range strikes.

     In recent decades, large-caliber anti-materiel rifles, typically firing 12.7 mm and 20 mm caliber cartridges, have been developed. The US Barrett M82A1 is probably the best-known such rifle. These weapons are typically used to strike critical, vulnerable targets such as computerized command and control vehicles, radio trucks, radar antennae, vehicle engine blocks and the jet engines of enemy aircraft. Anti-materiel rifles can be used against human targets, but the much higher weight of rifle and ammunition, and the massive recoil and muzzle blast, usually make them less than practical for such use. The Barrett M82 is credited with a maximum effective range of 1,800 m (1.1 mi); and it was with a .50BMG caliber McMillan TAC-50 rifle that Canadian Master Corporal Rob Furlong made the longest recorded (until 2010) confirmed sniper kill in history, when he shot a Taliban fighter at a range of 2,430 m (1.51 mi) in Afghanistan during Operation Anaconda in 2002.[3]

     Since then a British Army sniper beat the Canadian's record by 150 ft (46 m), by killing two Taliban insurgents at a range of 8,120 ft (2,470 m). He was using a standard issue British Army sniper rifle, the L115A3.[4]

Bullet Rotational Speed (RPM)

     Bullets leaving a rifled barrel can spin at over 300,000 revolutions per minute (rpm) depending on the muzzle velocity of the bullet and the pitch of the rifling. The rotational speed of the bullet can be calculated by using the formula below. The formula divides the number of inches in a foot (12) by the rate of twist that the barrel has. This number is multiplied by the muzzle velocity (MV) and the number of seconds in a minute (60). For example, a bullet with a muzzle velocity of 3,000 feet per second (910 m/s) leaving a barrel that twists once per foot (1/12") would rotate at 180,000rpm.[5]

    * MV x (12/twist rate in inches) x 60 = Bullet RPM

Example using a barrel that has a twist rate of 1 turn in 8" with a muzzle velocity of 3000 ft/s:

    * 3000 x (12/8) x 60 = 270,000

     Excessive rotational speed can exceed the bullet's designed limits and the resulting centrifugal force can cause the bullet to disintegrate in a radial fashion.[6] 

Caliber

    Rifles may be chambered in a variety of calibers, from .17 to .50 caliber. The term caliber essentially refers to the width of the bullet fired through a rifle's barrel. Larger caliber bullets have more overall power, but small caliber bullets can reach a higher velocity and have better penetration power[citation needed]. Armies have consistently attempted to find and procure the most lethal and accurate caliber for their firearms.

     The standard calibers used by the world's militaries tend to follow worldwide trends. These trends have significantly changed during the centuries of firearm design and re-design. Muskets were normally chambered for large calibers, such as .50 or .59, with the theory that these large bullets caused the most damage. During World War I and II, most rifles were chambered in .30 caliber, a combination of power and speed. Examples would be the British .303 Lee-Enfield, the American .30-06 M1903 Springfield, and the German 8mm Mauser K98. Within the past 40 years, however, military calibers have become smaller yet, with most armies favoring 5.56 mm or smaller rounds. Examples of firearms in this caliber are the American 5.56 mm M16 and the Russian 5.45 mm AK-74. The switch from .30 to 5.56 mm weapons was because the new rounds are lighter, which means a soldier can carry more of them, and because many military strategists believe the smaller bullet has better penetration power.