e2armory

Most modern semiautomatic firearms will, once the last round is fired, lock the slide, bolt, or analogous operating part open both as an indicator that the weapon is empty, and also to aid in returning to fire once a new magazine is inserted.

The slide release lever, sometimes not actually a lever but a button, switch, or toggle, will release the slide or bolt back into battery (firing position), usually chambering a round from the freshly-inserted magazine, if there is one.

A typical sequence of events is illustrated thus:

1) The trigger is pulled, dropping the hammer onto the firing pin, which strikes the primer of the chambered round.

2)The bullet exits the barrel, and the force of recoil or siphoned gas pressure from powder detonation operates the weapon - the empty brass case is ejected

3) Since there are no more bullets in the magazine, the slide or bolt catches on the magazine follower and is delayed in its forward progress; the slide release lever then holds the slide or bolt open.

4) The operator releases the empty magazine, and inserts a new one

5) The operator presses the slide release lever, which allows the slide or bolt to move forward, stripping the top round off of the new magazine and putting it into the chamber

6) The weapon is now ready to fire again. From the weapon's point of view, this sequence of actions is no different than if the magazine had not run out of bullets.

Assault carbine
As covered in the first paragraph of AK-47, by the beginning of WW2 it was apparent that the heavy, accurate, long-range rifles of yore were no longer suitable as general infantry arms. Smaller, lighter designs were needed, firing lower-powered cartridges, preferably with the capacity for controllable, fully-automatic fire. Rather than modify their existing rifles, the Russians decided to start afresh, basing their research around a new cartridge, the M1943. It is a tenet of firearms design that rifles tend to be designed around their cartridges, and not the other way around; the Russians put this into practice.

By the time of the German invasion three new weapon systems were envisaged, each firing the new cartridge, each one mirroring developments in the principal combatants in the Second World War. The first project looked to England's Lee-Enfield, and consisted of an old-style bolt-action rifle, a project presumably intended both as an emergency measure in case of a Russian collapse and the necessity of guerilla warfare, and to placate conservative elements in the Soviet military. This idea died a death and was quickly abandoned; the Lee-Enfield was the finest military bolt-action rifle of all time, but it had clearly had its day.

The second project called for a semi-automatic carbine for general issue, similar to the American M1 Garand, but cheaper to make and hopefully superior, as it was never expected that the allies would remain allied after the war. The third project was for an innovative new category of weapon that didn't yet have a name, but mirrored the German MP-42 - a select fire design half-way between a sub-machinegun and the aforementioned infantry carbine. This latter project eventually became Mikhail Kalashnikov's AK-47. The semi-automatic carbine was to become the SKS.

Sergei
It was designed by a man called Sergei Simonov, a designer at the Soviet Union's arsenal in Tula, where he worked with Feodore Tokarev, the veteran mind behind the Tokarev TT and SVT rifle (Mikhail Kalashnikov was meanwhile at Izmash in Izhevsk, one and a half thousand miles to the east). For Simonov the SKS was something of an obsession; his other designs - the Ptrs 41 anti-tank rifle and an unproduced sub-machinegun - being variations of the same basic mechanism. His prototype - originally called the AVS36, later 'Samozariadnyia Karabina Simonova', or 'Self-loading Carbine, Simonov' - dated as far back as 1931, but was hampered by being chambered for the 7.62x53mmR cartridge, a cartridge too powerful for the basic design, the force of the recoil causing mechanical failure during testing. Also against Simonov's design was the Tokarev SVT-38, a larger, more powerful and more complicated design which had been approved for general issue over the prototype SKS. The introduction of the 7.62x39mm M1943 cartridge gave the project a new lease of life, conversely dooming the unfortunate SVT, although the latter was to prove extremely influential on the design of post-war battle rifles. Whether Simonov and Tokarev's relationship suffered after that is lost to history.

Life and Times
Mechanically the SKS is gas-operated, with propellant gas bled from the barrel used to force a piston backwards, pushing open the bolt whilst extracting and feeding rounds. Whereas the AK-47 bolt rotates out of alignment with the chamber, the SKS bolt tilts, although neither design is overly complicated. In common with rifles of the period, the ten-round magazine remains fixed to the rifle whilst cartridges are loaded into the breech from above, either singly or via clips. Most versions had an integral bayonet that folded through 180 degrees downwards when not in use; this could also be used as a makeshift monopod when half-folded.

Even in 1945 the SKS was something of an anachronism. With a barrel four inches longer than the AK-47 the SKS was marginally more accurate and had greater range, against which it was semi-automatic only, and had a smaller magazine which took longer to reload. Nonetheless, it was cheaper and easier to make than the AK-47, and with similar ballistic performance to its assault rifle cousin it made an ideal training weapon; it also equipped second-line occupation troops, military police, artillerymen and other soldiers who, although off the front lines, nonetheless needed a weapon. Even today it remains in Russian service as a ceremonial arm.

The SKS entered limited production in 1944, and was used by some units in the final assault on Berlin, where it received glowing reviews from the troops. By 1945 production was in full swing, although the SKS never quite became the Soviet Union's main infantry arm. War surplus rifles continued in service for a few years, and the AK-47 started to replace the SKS from the early 1950s onwards. In 1955 Russian production was halted, although the next year production moved to China, with the result that the majority of SKS rifles in the world are Chinese. China used the rifle (the 'Type 56 Carbine') in parallel with their AK-47 (the 'Type 56 Assault Rifle') much as Russians had done, although from 1968 the SKS was replaced by the Type 68, an rifle which resembled the SKS but had AK-47 internals and a detachable magazine. Yugoslavian, East German and Romanian production started up in the late 1950s, with production continuing in various countries right up until the 1980s.

As with the AK-47 the SKS was produced and exported to regimes the Soviet Union supported, initially moreso than the AK-47, as the Soviet Union wished to retain an edge by keeping the AK-47 for themselves. During the Korean War, the SKS was issued to the best and brightest North Korean units, and it remained common in Vietnam, where it was much prized by US forces as, being semi-automatic, it could be legally posted home as a war trophy. More recently, irregular forces in the former Yugoslavia took advantage of domestic SKSs, as well as large quantities of ex-East German SKS rifles sold to Croatia after German reunification. As with the AK-47 it is popular amongst terrorists and guerrilla forces, although not to the same extent as a semi-automatic rifle requires more skill to use effectively; it is not possible to spray a car with bullets, the user has to aim as well. The continuing popularity can largely be put down to three things - reliability, cheapness, and the extreme proliferation of the M1943 cartridge.

SKS rifles are popular amongst civilian shooters in the United States, not least because prices rarely rise about $150; an SKS and a thousand rounds of ammunition can be had for $200, which from the perspective of a British writer is heartbreaking. Ammunition is cheap, the rifle's ten-round magazine and semiautomatic action fall within most legislation, and, on a psychological level, its old-fashioned appearance - a wooden stock, no pistol grip - does not conform to negative media stereotypes of an assault rifle. Much debate is conducted as to whether Russian or Chinese versions were better made, although the smart money appears to be on the 'Sino-Soviet' models - made in China during the years 1955-1956 in China by Russian engineers, as part of the technology transfer deal behind the shifted production.

Selected Sources
Apart from those mentioned in my writeup on the AK-47, which used the same cartridge and historical background:
http://www.simonov.net/
http://www.cruffler.com/Features/APR-02/review-April-02.html
http://world.guns.ru/rifle/rfl01-e.htm
http://www.gunsamerica.com/ (for prices)

At the beginning of the 19th century, the rifled flintlock musket was the accepted state of the art in shoulder-fired weapons. The combination of rifled barrel, cylindrical or conical projectile and reliable flintlock action made for a solid firearm, accurate and serviceable, with which an experienced shooter could get off perhaps three or four shots per minute. Use of the flintlock musket in both sniping and volleyed fire was widespread among armies of the period.

There were, of course, disadvantages to the musket which most folks who used it couldn't wait to be rid of - and in 1836, one of the most important advances in shoulder arms since the flintlock was unveiled in Germany. The gunsmith Johann Nicholas von Dreyse produced the first needle gun, a weapon which would become famous as the weapon of the formidable Prussian mercenaries and armies.

The needle gun was, essentially, the first modern breech-loading military rifle. It used standardized, manufactured cartridges of .607 caliber which included bullet, charge and primer in one unit for easier reloading. At a stroke, this gun changed the nature of military rifles forever, and a surge in new designs began, leading in the Americas to the Winchester and Spencer rifles, and in Germany to the Mauser rifle used through World War II.

The needle gun used paper cartridges. The bullet was secured at the front, with the powder (it was black powder) contained at the rear inside the paper tube. There was a small charge of primer (fulminate) between the bullet and the main charge. To load the needle gun, a turn of a knob cocked a spring and cranked back a breechblock which allowed the cartridge to slide into place. When the breechblock was moved back, a small hole at the center of the front of this cylinder faced the back of the cartridge. At the trigger pull, the spring forced a steel needle out this hole and through both the cartridge casing of paper and the black powder, to strike the primer against the back of the bullet. This meant that the charge ignited from the front, which was important in an era of limited machining technology. Breechloaders tended to leak gas at their joins, lessening the velocity (and hence range and accuracy) of the bullet. The front-burning powder in the needle gun meant that not only did the rear of the cartridge and charge serve to further seal the breech, but the impulse of the charge did not throw the charge itself down the barrel as could occur with rear-igniting charges.

The needle was the precursor to the modern firing pin. The weapon was adopted by various armies in Germany. The French rejected it for several reasons; they cited its leaky breechloading nature, the fragility of the needles, and the complexity of the mechanism. It was, however, accurate and lethal out to around 'eight hundred paces' according to contemporary sources.

There were, of course, shortcomings in the design. The needles were (as the French pointed out) prone to breakage. Despite the ease of replacement and the ready size and availability of spares, it was an inconvenient glitch on the battlefield. The paper cartridges were fairly easily damaged. The breechloading design and consequent loss of breech pressure did, in fact, limit the range of the gun compared to contemporary muzzle-loaders.

On the other hand, it made the standardization of cartridged ammunition a practical reality; its interchangeable parts made for ready battlefield maintenance and resupply, and the quick action of loading meant a competent shooter could suddenly crank out upwards of ten shots per minute, rather than three. Furthermore, it could be loaded while on the move or atop a horse, and as a breechloader could be reloaded more easily while prone or inside a confined space. The ammunition, although vulnerable to damp and damage, was nevertheless much, much more handy than the separate charge/primer/bullet systems used in muskets.

Various versions of the needle gun were eventually produced in other countries; the U.S. saw one known as the Klein patent needle gun, and the French, Belgians and British all experimented with the design. By the middle of the century, however, it was clear that later refinements which used firing pins or hammers, striking primers at the rear of a rigid cartridge, were ascendant. These systems were further iterated into the first repeating arms, and the needle gun was left behind. It had, however, begun the push towards unit cartridge, standard loading weapons which made the repeaters (and, indeed, all standard semi-automatic and automatic rifles up to today) possible.

Sources:

• "Dreyse's Needle-Gun and Training of the Prussian Soldier" from Chambers' Journal, http://www.researchpress.co.uk/firearms/firearms.htm
• Various Encyclopedae
• Robert D. Ball, Springfield Armory Shoulder Weapons 1795-1968. Antique Trader Press, 1999.
• Lecture notes, MIT 17.4xx Grand Strategy and Military Doctrine, Professor Barry Posen, 1996