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Subsonic Ammunition
Subsonic ammunition is ammunition designed to operate at velocities below the speed of sound, which at standard conditions is or Mach 1. This avoids the supersonic shockwave or "crack" of a supersonic bullet, which, particularly for suppressed firearms, influences the loudness of the shot. Subsonic ammunition usually uses heavier bullets to retain as much energy as possible at the lower velocities. Some subsonic ammunition is used in non-suppressed firearms to gain the advantages of heavier bullet weights. __TOC__ Standard calibers Subsonic versions of standard rounds In this instance, heavier bullets are loaded in standard ammunition, which reduces muzzle velocity below the speed of sound. As an example, the very common 9×19mm Parabellum standard military round is a bullet at velocities typically around . Subsonic loads for 9mm commonly use bullets at velocities of . For these ammunition loads, balancing bullet weight and velocity are required to ensure that the ammun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammunition
Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weapons that create the effect on a target (e.g., bullets and warheads). The purpose of ammunition is to project a force against a selected target to have an effect (usually, but not always, lethal). An example of ammunition is the firearm cartridge, which includes all components required to deliver the weapon effect in a single package. Until the 20th century, black powder was the most common propellant used but has now been replaced in nearly all cases by modern compounds. Ammunition comes in a great range of sizes and types and is often designed to work only in specific weapons systems. However, there are internationally recognized standards for certain ammunition types (e.g., 5.56×45mm NATO) that enable their use across different weapo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Sound
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as well as the medium through which a sound wave is propagating. At , the speed of sound in air is about . The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In colloquial speech, ''speed of sound'' refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids. For example, while sound travels at in air, it travels at in water (almost 4.3 times as fast) and at in iron (almost 15 times as fast). In an exceptionally stiff material such as diamond, sound travels a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach Number
Mach number (M or Ma) (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It is named after the Moravian physicist and philosopher Ernst Mach. : \mathrm = \frac, where: : is the local Mach number, : is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and : is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach1, the local flow velocity is equal to the speed of sound. At Mach0.65, is 65% of the speed of sound (subsonic), and, at Mach1.35, is 35% faster than the speed of sound (supersonic). Pilots of high-altitude aerospace vehicles use flight Mach number to express a vehicle's true airspeed, but the flow field around a vehicle varies in three dimensions, with corresponding variations in local Mach number. The local spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonic Boom
A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear. A decibel is the primary unit measurement of sound. "A thunderclap is incredibly loud, producing levels between 100 and 120 dBA (Decibel, decibels A)- the equivalent of standing near a jet during take-off." The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a sonic boom in miniature. Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures. This led to prohibition of routine supersonic flight overland. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle, the nuisance due to the sonic booms may be reduced to the point that overland super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Suppressor
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that reduces the acoustic intensity Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m2 ... of the muzzle report (sound of a gunshot) and muzzle rise when a gun (firearm or air gun) is discharged, by modulating the speed and pressure of the propellant gas from the muzzle and hence suppressing the muzzle blast. Like other muzzle devices, a silencer can be a detachable accessory mounted to the muzzle, or an integral part of the gun barrel, barrel. A typical silencer is a metallic (usually stainless steel or titanium) cylinder containing internal sound baffles, with a hollow bore to allow the projectile (bullet) to exit normally. During firing, the bullet flies through the bore with litt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
9×19mm Parabellum
The 9×19mm Parabellum (also known as 9mm Parabellum or 9mm Luger or simply 9mm) is a rimless, tapered firearms cartridge. Originally designed by Austrian firearm designer Georg Luger in 1901, it is widely considered the most popular handgun and submachine gun cartridge due to its low cost and extensive availability. It is a standard cartridge for NATO forces as well as in many non-NATO countries. Since the cartridge was designed for the Luger semi-automatic pistol, it has been given the designation of 9mm Luger by the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) and the Commission internationale permanente pour l'épreuve des armes à feu portatives (CIP). A 2007 US survey concluded that "about 60 percent of the firearms in use by police are 9mm arabellum and credited 9×19mm Parabellum pistol sales with making semiautomatic pistols more popular than revolvers.Adler, Jerry, et al. "Story of a Gun." ''Newsweek'' 149.18 (30 April 2007): 36–39. MasterFILE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
45 ACP
The .45 ACP (Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it was adopted as the standard chambering for Colt's M1911 pistol. The round was developed due to a lack of stopping power experienced in the Moro Rebellion in places like Sulu. The issued ammunition, .38 Long Colt, had proved inadequate, motivating the search for a better cartridge. This experience and the Thompson–LaGarde Tests of 1904 led the Army and the Cavalry to decide that a minimum of .45 caliber was required in a new handgun. The standard issue military .45 ACP round uses a 230-grain (14.9 g) round nose projectile that travels at approximately 830 feet per second (250 m/s) when fired from a government-issue M1911A1 pistol. It operates at a relatively low maximum chamber pressure rating of , compared to for both 9mm Parab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grain (unit)
A grain is a unit of measurement of mass, and in the troy weight, avoirdupois, and apothecaries' systems, equal to exactly milligrams. It is nominally based upon the mass of a single ideal seed of a cereal. From the Bronze Age into the Renaissance, the average masses of wheat and barley grains were part of the legal definitions of units of mass. Expressions such as "thirty-two grains of wheat, taken from the middle of the ear" appear to have been ritualistic formulas, essentially the premodern equivalent of legal boilerplate. Another source states that it was defined such that 252.458 units would balance of distilled water at an ambient air-water pressure and temperature of and respectively. Another book states that Captain Henry Kater, of the British Standards Commission, arrived at this value experimentally. The grain was the legal foundation of traditional English weight systems, and is the only unit that is equal throughout the troy, avoirdupois, and apothecaries' sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feet Per Second
The foot per second (plural feet per second) is a unit of both speed (scalar) and velocity (vector quantity, which includes direction). It expresses the distance in feet (ft) traveled or displaced, divided by the time in seconds (s). The corresponding unit in the International System of Units (SI) is the meter per second. Abbreviations include ft/s, fps, and the scientific notation ft s−1. Conversions See also *Foot per second squared, a corresponding unit of acceleration. *Feet per minute The foot (plural, : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb (anatomy), limb which bears weight and allows animal locomotion, locomotion. In many animals with feet, the foot is a separate o ... References Units of velocity Customary units of measurement in the United States {{United States Customary Units ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
300 Whisper
3 (three) is a number, numeral and digit. It is the natural number following 2 and preceding 4, and is the smallest odd prime number and the only prime preceding a square number. It has religious or cultural significance in many societies. Evolution of the Arabic digit The use of three lines to denote the number 3 occurred in many writing systems, including some (like Roman and Chinese numerals) that are still in use. That was also the original representation of 3 in the Brahmic (Indian) numerical notation, its earliest forms aligned vertically. However, during the Gupta Empire the sign was modified by the addition of a curve on each line. The Nāgarī script rotated the lines clockwise, so they appeared horizontally, and ended each line with a short downward stroke on the right. In cursive script, the three strokes were eventually connected to form a glyph resembling a with an additional stroke at the bottom: ३. The Indian digits spread to the Caliphate in the 9th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
300 AAC Blackout (7
The .300 AAC Blackout (designated as the 300 BLK by the SAAMI and 300 AAC Blackout by the C.I.P. or 300 AAC Blackout'' C.I.P. TDCC sheet 300 ACC Blackout/ref>), also known as 7.62×35mm, is an intermediate cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. The cartridge yields increased performance in shorter barrels and effective subsonic performance for suppressor use when compared to 5.56mm NATO. The 300 AAC Blackout utilizes standard 5.56mm NATO magazines and components with the exception of the barrel. History While 5.56×45mm NATO has enjoyed widespread acceptance in military circles, the nature of the missions encountered by some special operations groups often demand a round that provides better performance than that available in the high-energy, standard velocity rounds, and subsonic performance greater than standard 9×19mm Parabellum (the ubiquitous pistol and submachine gun) round. To meet this demand, AAC de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
338 Whisper
__NOTOC__ Year 338 ( CCCXXXVIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Ursus and Polemius (or, less frequently, year 1091 ''Ab urbe condita''). The denomination 338 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * The Romans, allied with the Goths, arrive in the north of the Roman Empire to protect the Danube frontier. * Emperor Constantius II intervenes against the Persians in Armenia. Persia * Shapur II, king of the Persian Empire, begins a widespread persecution of Christians. He orders forcible conversions to the state religion, Zoroastrianism, lest the Christians disrupt his realm while he is away fighting the Romans in Armenia and Mesopotamia. Asia * Tuoba Yihuai, ruler of the Tuoba Dai clan, dies and is succ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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