1.
Caliber
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In guns, particularly firearms, caliber or calibre is the approximate internal diameter of the barrel, or the diameter of the projectile it fires, in hundredths or sometimes thousandths of an inch. For example, a 45 caliber firearm has a diameter of.45 of an inch. Barrel diameters can also be expressed using metric dimensions, as in 9mm pistol, when the barrel diameter is given in inches, the abbreviation cal can be used. Good performance requires a bullet to closely match the diameter of a barrel to ensure a good seal. While modern cartridges and cartridge firearms are referred to by the cartridge name. Firearm calibers outside the range of 17 to 50 exist, but are rarely encountered. Larger calibers, such as.577.585.600.700, the.950 JDJ is the only known cartridge beyond 79 caliber used in a rifle. Referring to artillery, caliber is used to describe the length as multiples of the bore diameter. A 5-inch 50 calibre gun has a diameter of 5 in. The main guns of the USS Missouri are 1650 caliber, makers of early cartridge arms had to invent methods of naming the cartridges, since no established convention existed then. One of the early established cartridge arms was the Spencer repeating rifle, later various derivatives were created using the same basic cartridge, but with smaller-diameter bullets, these were named by the cartridge diameter at the base and mouth. The original No.56 became the. 56-56, and the smaller versions. 56-52. 56-50, the. 56-52, the most common of the new calibers, used a 50-cal bullet. Optionally, the weight in grains was designated, e. g. 45-70-405. Variations on these methods persist today, with new cartridges such as the.204 Ruger, metric diameters for small arms refer to cartridge dimensions and are expressed with an × between the bore diameter and the length of the cartridge case, for example,7. 62×51 NATO. This indicates that the diameter is 7. 62mm, loaded in a case 51mm long. Similarly, the 6. 5×55 Swedish cartridge has a diameter of 6.5 mm. An exception to rule is the proprietary cartridge used by U. S. maker Lazzeroni. The following table lists commonly used calibers where both metric and imperial are used as equivalents
2.
Cartridge (weaponry)
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Military and commercial producers continue to pursue the goal of caseless ammunition. A cartridge without a bullet is called a blank, One that is completely inert is called a dummy. Some artillery ammunition uses the same concept as found in small arms. In other cases, the shell is separate from the propellant charge. In popular use, the bullet is often misused to refer to a complete cartridge. The cartridge case seals a firing chamber in all directions excepting the bore, a firing pin strikes the primer and ignites it. The primer compound deflagrates, it does not detonate, a jet of burning gas from the primer ignites the propellant. Gases from the burning powder pressurize and expand the case to seal it against the chamber wall and these propellant gases push on the bullet base. In response to pressure, the bullet will move in the path of least resistance which is down the bore of the barrel. After the bullet leaves the barrel, the pressure drops to atmospheric pressure. The case, which had been expanded by chamber pressure. This eases removal of the case from the chamber, brass is a commonly used case material because it is resistant to corrosion. A brass case head can be work-hardened to withstand the pressures of cartridges. The neck and body portion of a case is easily annealed to make the case ductile enough to allow reforming so that it can be reloaded many times. Steel is used in some plinking ammunition, as well as in military ammunition. Steel is less expensive than brass, but it is not feasible to reload, Military forces typically consider small arms cartridge cases to be disposable, one-time-use devices. However, case weight affects how much ammunition a soldier can carry, conversely, steel is more susceptible to contamination and damage so all such cases are varnished or otherwise sealed against the elements. One downside caused by the strength of steel in the neck of these cases is that propellant gas can blow back past the neck
3.
Imperial units
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The system of imperial units or the imperial system is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The Imperial units replaced the Winchester Standards, which were in effect from 1588 to 1825, the system came into official use across the British Empire. The imperial system developed from what were first known as English units, the Weights and Measures Act of 1824 was initially scheduled to go into effect on 1 May 1825. However, the Weights and Measures Act of 1825 pushed back the date to 1 January 1826, the 1824 Act allowed the continued use of pre-imperial units provided that they were customary, widely known, and clearly marked with imperial equivalents. Apothecaries units are mentioned neither in the act of 1824 nor 1825, at the time, apothecaries weights and measures were regulated in England, Wales, and Berwick-upon-Tweed by the London College of Physicians, and in Ireland by the Dublin College of Physicians. In Scotland, apothecaries units were unofficially regulated by the Edinburgh College of Physicians, the three colleges published, at infrequent intervals, pharmacopoeiae, the London and Dublin editions having the force of law. The Medical Act of 1858 transferred to The Crown the right to publish the official pharmacopoeia and to regulate apothecaries weights, Metric equivalents in this article usually assume the latest official definition. Before this date, the most precise measurement of the imperial Standard Yard was 0.914398416 metres, in 1824, the various different gallons in use in the British Empire were replaced by the imperial gallon, a unit close in volume to the ale gallon. It was originally defined as the volume of 10 pounds of distilled water weighed in air with brass weights with the standing at 30 inches of mercury at a temperature of 62 °F. The Weights and Measures Act of 1985 switched to a gallon of exactly 4.54609 l and these measurements were in use from 1826, when the new imperial gallon was defined, but were officially abolished in the United Kingdom on 1 January 1971. In the USA, though no longer recommended, the system is still used occasionally in medicine. The troy pound was made the unit of mass by the 1824 Act, however, its use was abolished in the UK on 1 January 1879, with only the troy ounce. The Weights and Measures Act 1855 made the pound the primary unit of mass. In all the systems, the unit is the pound. For the yard, the length of a pendulum beating seconds at the latitude of Greenwich at Mean Sea Level in vacuo was defined as 39.01393 inches, the imperial system is one of many systems of English units. Although most of the units are defined in more than one system, some units were used to a much greater extent, or for different purposes. The distinctions between these systems are not drawn precisely. One such distinction is that between these systems and older British/English units/systems or newer additions, the US customary system is historically derived from the English units that were in use at the time of settlement
4.
.303 British
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The.303 British or 7. 7×56mmR, is a. 303-inch calibre rimmed rifle cartridge first developed in Britain as a black-powder round put into service in December 1888 for the Lee–Metford rifle. In 1891 the cartridge was adapted to use smokeless powder and it was the standard British and Commonwealth military cartridge from 1889 until the 1950s when it was replaced by the 7. 62×51mm NATO. The.303 British has 3.64 ml cartridge case capacity, americans would define the shoulder angle at alpha/2 ≈17 degrees. The common rifling twist rate for this cartridge is 254 mm,5 grooves, Ø lands =7.70 millimetres, Ø grooves =7.92 millimetres, land width =2.12 millimetres and the primer type is Berdan or Boxer. Rulings the.303 British can handle up to 365.00 MPa Pmax piezo pressure, regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C. I. P. pressure to certify for sale to consumers. This means that.303 British chambered arms in C. I. P, regulated countries are currently proof tested at 456.00 MPa PE piezo pressure. The SAAMI Maximum Average Pressure for this cartridge is 49,000 psi piezo pressure, the measurement. 303-inch is the nominal size of the bore measured between the lands which follows the older black powder nomenclature. Measured between the grooves, the size of the bore is. 311-inch. Bores for many.303 military surplus rifles are found ranging from around. 309-inch up to. 318-inch. Recommended bullet diameter for standard.303 British cartridges is. 312-inch, the bolt thrust of the.303 British is relatively low compared to many other service rounds used in the early 20th century. The original.303 British service cartridge employed black powder as a propellant, and was adopted for the Lee–Metford rifle, ballistite was a stick-type smokeless powder composed of soluble nitrocellulose and nitroglycerine. Unlike Cordite, Riflelite was a powder, and contained no nitroglycerine. After extensive testing, the Committee on Explosives selected Cordite for use in the Mark II.303 British service cartridge, the initial.303 Mark I and Mk II service cartridges employed a 215-grain, round-nosed, copper-nickel full-metal-jacketed bullet with a lead core. After tests determined that the bullet had too thin a jacket when used with cordite. This led to the introduction of the Cartridge S. A. Ball.303 inch Cordite Mark III, similar hollow-point bullets were used in the Mk IV and Mk V loadings, which were put into mass production. The design of the Mk IV hollow-point bullet shifted bullet weight rearwards, improving stability, the remaining stocks were used for target practice. The concern about expanding bullets was brought up at the 1899 Hague Convention by Swiss, the British and American defense was that they should not focus on specific bullet designs, like hollow-points, but instead on rounds that caused superfluous injury. The parties in the end agreed to abstain from using expanding bullets, as a result, the Mark III and other expanding versions of the.303 were not issued during the Second Boer War
5.
TT pistol
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The TT-30 is a Russian semi-automatic pistol. It served until 1952, when it was replaced by the Makarov pistol, in 1930, the Revolutionary Military Council approved a resolution to test new small arms to replace its aging Nagant M1895 revolvers. During these tests, on 7 January 1931, the potential of a designed by Fedor Tokarev was noted. A few weeks later,1,000 TT-30s were ordered for trials. The TT-30 was manufactured between 1930 and 1936, with about 93,000 being produced, but even as the TT-30 was being put into production, design changes were made to simplify manufacturing. This redesigned pistol was the TT-33, most TT-33s were issued to officers. The TT-33 was widely used by Soviet troops during World War II, in other areas the TT-33 differs more from Brownings designs — it employs a much simpler hammer/sear assembly than the M1911. This assembly is removable from the pistol as a modular unit, Soviet engineers made several alterations to make the mechanism easier to produce and maintain, most notably the simplifications of the barrels locking lugs, allowing fewer machining steps. Some models use a captive recoil spring secured to the rod which does depend on the barrel bushing to hold it under tension. The TT-33 is chambered for the 7. 62×25mm Tokarev cartridge, the 7. 62×25mm cartridge is powerful, has an extremely flat trajectory, and is capable of penetrating thick clothing and soft body armor. Able to withstand tremendous abuse, large numbers of the TT-33 were produced during World War II, in modern times the robust TT-33 has been converted to many extremely powerful cartridges including.38 Super and 9×23mm Winchester. Many imported variants have manual safeties added, which vary greatly in placement, the Wehrmacht captured a fair number of TT-33s and issued them to units under the Pistole 615 designation. This was made possible by the fact that Russian 7.62 mm Model 1930 Type P cartridges were nearly identical to the German 7. 63×25mm Mauser cartridge, therefore, German ammunition could be used in captured Russian arms, but not vice versa. Due to much higher pressures, the Russian cartridges should never be used in the German Mauser pistols, such use could be very dangerous. Interarms marketed World War II-surplus Russian-made Tokarevs in Europe and the United States as the Phoenix and they had new wooden grips with a phoenix design on them and were overstamped INTERARMS on the barrel. Later gun laws banned their sale due to their lack of a safety, the TT-33 was eventually replaced by the 8-round, 9×18mm Makarov PM pistol in 1952. Production of the TT-33 in Russia ended in 1954, but copies were made by other countries. At one time or another most communist or Soviet bloc countries made a variation of the TT-33 pistol, the TT pistol was copied in China as the Type 51, Type 54, M20, and TU-90. 62×25mm caliber
6.
Submachine gun
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A submachine gun is a magazine-fed, automatic carbine designed to fire pistol cartridges. The term submachine gun was coined by John T. Thompson, the submachine gun was developed during World War I. At its zenith during World War II, millions of SMGs were made, after the war, new SMG designs appeared frequently. However, by the 1980s, SMG usage decreased, today, submachine guns have been largely replaced by assault rifles, which have a greater effective range and are capable of penetrating the helmets and body armor used by modern infantrymen. Carbine-type automatic weapons firing pistol rounds were developed during the stages of World War I by Italy, Germany. Their improved firepower and portability offered an advantage in trench warfare, in 1915, the Italians introduced the Villar-Perosa aircraft machine gun. It fired pistol-caliber 9mm Glisenti ammunition, but was not a true submachine gun and this odd design was then modified into the Beretta OVP carbine-type submachine gun, which then evolved into the Beretta Model 1918 after the end of World War I. Both the Beretta OVP and the Model 1918 had a wooden stock, a 25-round top-fed box magazine. The Germans initially used heavier versions of the P08 pistol equipped with a larger-capacity snail-drum magazine, by 1918, Bergmann Waffenfabrik had developed the MP18, the first practical submachine gun. This weapon fired the 9×19mm Parabellum round and used the same 32-round snail-drum magazine as the Luger P-08, the MP18 was used in significant numbers by German stormtroopers employing infiltration tactics, achieving some notable successes in the final year of the war. However, these were not enough to prevent Germanys collapse in November 1918, after World War I, the MP18 would evolve into the MP28/II SMG, which incorporated a simple 32-round box magazine, a semi & full auto selector, and other minor improvements. The Thompson submachine gun had been in development at approximately the time as the Bergmann. However, the war ended before prototypes could be shipped to Europe, although it had missed its chance to be the first purpose-designed submachine gun to enter service, it became the basis for later weapons and had the longest active service life of the three. However, the FBI and other U. S. police forces themselves showed no reluctance to use, eventually, the submachine gun was gradually accepted by many military organizations, especially as World War II loomed, with many countries developing their own designs. The Italians were among the first to develop submachine guns during World War I, however, they were slow to produce them during World War II. The Beretta Model 1938 was not available in numbers until 1943. The 38 was made in a series of improved and simplified models all sharing the same basic layout. The Beretta has two triggers, the front for semi-auto and rear for full-auto, most models use standard wooden stocks, although some models were fitted with an MP 40-style under-folding stock and are commonly mistaken for the German SMG
