Muzzle velocity

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Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/shots or shell) with respect to [1] the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). [2] Firearm muzzle velocities range from approximately 120 m/s (390 ft/s) to 370 m/s (1,200 ft/s) in black powder muskets, [3] to more than 1,200 m/s (3,900 ft/s) [4] in modern rifles with high-velocity cartridges such as the .220 Swift and .204 Ruger, all the way to 1,700 m/s (5,600 ft/s) [5] for tank guns firing kinetic energy penetrator ammunition. To simulate orbital debris impacts on spacecraft, NASA launches projectiles through light-gas guns at speeds up to 8,500 m/s (28,000 ft/s). [6]

Contents

Projectile velocity

For projectiles in unpowered flight, its velocity is highest at leaving the muzzle and drops off steadily because of air resistance. Projectiles traveling less than the speed of sound (about 340 m/s (1,100 ft/s) in dry air at sea level) are subsonic, while those traveling faster are supersonic and thus can travel a substantial distance and even hit a target before a nearby observer hears the "bang" of the shot. Projectile speed through air depends on a number of factors such as barometric pressure, humidity, air temperature and wind speed. Some high-velocity small arms have muzzle velocities higher than the escape velocities of some Solar System bodies such as Pluto and Ceres, meaning that a bullet fired from such a gun on the surface of the body would leave its gravitational field; however no arms are known with muzzle velocities that can overcome Earth's gravity (and atmosphere) or those of the other planets or the Moon.

While traditional cartridges cannot generally achieve a Lunar escape velocity (approximately 2,300 m/s (7,500 ft/s)) or higher due to modern limitations of action and propellant, a 1 gram (15.4324 grains ) projectile was accelerated to velocities exceeding 9,000 m/s (30,000 ft/s) at Sandia National Laboratories in 1994. The gun operated in two stages. First, burning gunpowder was used to drive a piston to pressurize hydrogen to 10,000 atm. The pressurized gas was then released to a secondary piston, which traveled forward into a shock-absorbing "pillow", transferring the energy from the piston to the projectile on the other side of the pillow.

This discovery might indicate that future projectile velocities exceeding 1,500 m/s (4,900 ft/s) have to have a charging, gas-operated action that transfers the energy, rather than a system that uses primer, gunpowder, and a fraction of the released gas. A .22 LR cartridge is approximately three times the mass of the projectile in question. This may be another indication that future arms developments will take more interest in smaller caliber rounds, especially due to modern limitations such as metal usage, cost, and cartridge design. In a side by side comparison with the .50 BMG (43g), the 15.4324 gr (1 g) titanium round of any caliber released almost 28 times the energy of the .50 BMG, with only a 27% mean loss in momentum. Energy, in most cases, is what is lethal to the target, not momentum. [7]

Conventional guns

In conventional guns, muzzle velocity is determined by the quantity of the propellant, its quality (in terms of chemical burn speed and expansion), the mass of the projectile, and the length of the barrel. A slower-burning propellant needs a longer barrel to finish its burn before leaving, but conversely can use a heavier projectile. This is a mathematical tradeoff. [8] A faster-burning propellant may accelerate a lighter projectile to higher speeds if the same amount of propellant is used. Within a gun, the gaseous pressure created as a result of the combustion process is a limiting factor on projectile velocity. Consequently, propellant quality and quantity, projectile mass, and barrel length must all be balanced to achieve safety and to optimize performance.

Longer barrels give the propellant force more time to work on propelling the bullet. [8] For this reason longer barrels generally provide higher velocities, everything else being equal. As the bullet moves down the bore, however, the propellant's gas pressure behind it diminishes. Given a long enough barrel, there would eventually be a point at which friction between the bullet and the barrel, and air resistance, would equal the force of the gas pressure behind it, and from that point, the velocity of the bullet would decrease.

Rifles

Rifled barrels have spiral twists carved inside them that spin the bullet so that it remains stable in flight, in the same way an American football thrown in a spiral will fly in a straight, stable manner. This mechanism is known as rifling. Longer barrels provide more opportunity to rotate the bullet before it leaves the gun. As such, longer barrels increase the overall precision of the weapon. If one examines shot groups on a paper target from a 2-inch (51 mm) barrel, a 4-inch (100 mm) barrel, and a 6-inch (150 mm) barrel, one will observe how the longer barrels produce "tighter" grouping, with bullets landing closer together on the target.

A bullet, while moving through its barrel, is being pushed forward by the gas expanding behind it. This gas was created when the trigger was pulled, causing the firing pin to strike the primer, which in turn ignited the solid propellant packed inside the bullet cartridge, making it combust while situated in the chamber. Once it leaves the barrel, the force of the expanding gas ceases to propel the bullet forth. [9] When a bullet is fired from a handgun with a 2-inch (51 mm) barrel, the bullet only has a 2-inch (51 mm) "runway" to be spun before it leaves the barrel. Likewise, it has only a 2-inch (51 mm) space in which to accelerate before it must fly without any additional force behind it. In some instances, the powder may not have even been fully burned in guns with short barrels. So, the muzzle velocity of a 2-inch (51 mm) barrel is less than that of a 4-inch (100 mm) barrel, which is less than that of a 6-inch (150 mm) barrel.

Large naval guns will have high length-to-diameter ratios, ranging between 38:1 to 50:1. This length ratio maximizes the projectile velocity. There is much interest in modernizing naval weaponry by using electrically powered railguns, which shoot projectiles using an electromagnetic pulse. These overcome the limitations noted above. With these railguns, a constant acceleration is provided along the entire length of the device by means of the electromagnetic pulse. This greatly increases the muzzle velocity. Another significant advantage of railguns is not requiring explosive propellant. [10] The result of this is that a ship will not need to transport propellant and that a land-station will not have to maintain an inventory of it either. Explosive propellant, stored in large quantities, is susceptible to explosion. [11] While this can be mitigated with safety precautions, [11] railguns eschew the need for such measures altogether. Even the projectile internal charges may be eliminated due to the already high velocity. This means the projectile becomes a strictly kinetic weapon.

Categories of velocity

The United States Army defines different categories of muzzle velocity for different classes of weapons: [12]

WeaponLow velocityHigh velocity Hypervelocity
Artillery cannons Less than 396 m/s (1,299 ft/s)Between 910 and 1,070 m/s (3,000–3,500 ft/s)Greater than 1,070 m/s (3,500 ft/s)
Tank guns -Between 470 and 1,020 m/s (1,550–3,350 ft/s)Greater than 1,020 m/s (3,350 ft/s)
Small arms -Between 1,070 and 1,520 m/s (3,500–5,000 ft/s)Greater than 1,520 m/s (5,000 ft/s)

See also

Related Research Articles

Cartridge (firearms) Ammunition consisting of a casing, projectile, propellant and primer

A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for the practical purpose of convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often informally used to refer to a complete cartridge, it is correctly used only to refer to the projectile.

Rifling Gunsmithing technique

In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the projectile longitudinally by conservation of angular momentum, improving its aerodynamic stability and accuracy over smoothbore designs.

Air gun Gun that uses compressed air to launch projectiles

An air gun, air rifle or airgun, is a gun that shoots projectiles pneumatically with compressed air or other gases that are mechanically pressurized without involving any chemical reactions, in contrast to a firearm, which pressurizes gases chemically via oxidation of combustible propellants that generates propulsive energy by breaking molecular bonds.

Caliber Internal diameter of the barrel of a gun

In guns, particularly firearms, caliber is the specified nominal internal diameter of the gun barrel bore - regardless of how or where the bore is measured and whether the finished bore matches that specification. It is measured in inches or in millimeters. In the United States it is expressed in hundredths of an inch; in Great Britain in thousandths; in Europe and elsewhere in millimeters. For example, a "45 caliber" firearm has a barrel diameter of roughly 0.45 inches (11 mm). Barrel diameters can also be expressed using metric dimensions. For example, a "9 mm pistol" has a barrel diameter of about 9 millimeters. Due to the fact that metric and US customary units do not convert evenly at this scale, metric conversions of caliber measured in decimal inches are typically approximations of the precise specifications in non-metric units, and vice versa.

Recoil

Recoil is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force required to accelerate something will evoke an equal but opposite reactional force, which means the forward momentum gained by the projectile and exhaust gases (ejectae) will be mathematically balanced out by an equal and opposite momentum exerted back upon the gun. In hand-held small arms, the recoil momentum will be eventually transferred to the ground, but will do so through the body of the shooter hence resulting in a noticeable impulse commonly referred to as a "kick".

Rimfire ammunition

Rimfire ammunition is a type of firearm metallic cartridge whose primer is located within a hollow circumferential rim protruding from the base of its casing. When fired, the gun's firing pin will strike and crush the rim against the edge of the barrel breech, sparking the primer compound within the rim, and in turn ignite the propellant within the case. Invented in 1845, by Louis-Nicolas Flobert, the first rimfire metallic cartridge was the .22 BB Cap cartridge, which consisted of a percussion cap with a bullet attached to the top. While many other different cartridge priming methods have been tried since the 19th century, only rimfire and the later centerfire cartridges survive to the present day with regular usages. The .22 Long Rifle rimfire cartridge, introduced in 1887, is by far the most common ammunition in the world today in terms of units sold.

Sabot (firearms)

A sabot is a supportive device used in firearm/artillery ammunitions to fit/patch around a projectile, such as a bullet/slug or a flechette-like projectile, and keep it aligned in the center of the barrel when fired. It allows a narrower projectile with high sectional density to be fired through a barrel of much larger bore diameter with maximal accelerative transfer of kinetic energy. After leaving the muzzle, the sabot typically separates from the projectile in flight, diverting only a very small portion of the overall kinetic energy.

Gun barrel Firearm component which guides the projectile during acceleration

A gun barrel is a crucial part of gun-type ranged weapons such as small firearms, artillery pieces and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pressure gas(es) is used to propel a projectile out of the front end (muzzle) at a high velocity. The hollow interior of the barrel is called the bore, and the diameter of the bore is called its caliber, usually measured in inches or millimetres.

.22 Long Rifle

The .22 Long Rifle or simply .22 LR is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of rifles, pistols, revolvers, smoothbore shotguns, and submachine guns.

Internal ballistics, a subfield of ballistics, is the study of the propulsion of a projectile.

Blank (cartridge)

A blank is a firearm cartridge that generates a muzzle flash and an explosive sound like any normal gunshots, and the firearm experiences a recoil capable of cycling its action, but without shooting a projectile. Blanks are often used for shooting simulations that have no need for ballistic results but still demand light and sound effects, such as in historical reenactments, special effects for theatre, movie and television productions, combat training, for signalling, and cowboy mounted shooting. Specialised blank cartridges are also used for their propellant force in fields as varied as construction, shooting sports, and fishing and general recreation.

The .30-06 Springfield cartridge, 7.62×63mm in metric notation and called ".30 Gov't '06" by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in use until the late-1970s. The ".30" refers to the caliber of the bullet in inches. The "06" refers to the year the cartridge was adopted, 1906. It replaced the .30-03, 6mm Lee Navy, and .30-40 Krag cartridges. The .30-06 remained the U.S. Army's primary rifle and machine gun cartridge for nearly 50 years before being replaced by the 7.62×51mm NATO and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. It remains a very popular sporting round, with ammunition produced by all major manufacturers.

.22 CB

The .22 CB cap is a more powerful version of the .22 BB cap rimfire metallic cartridge, which was invented by Louis-Nicolas Flobert in 1845. The .22 BB cap and .22 CB cap are interchangeable and are relatively quiet, low velocity cartridges, designed for indoor target shooting.

Light-gas gun Highly specialized gun designed to generate very high velocities

The light-gas gun is an apparatus for physics experiments. It is a highly specialized gun designed to generate extremely high velocities. It is usually used to study high-speed impact phenomena, such as the formation of impact craters by meteorites or the erosion of materials by micrometeoroids. Some basic material research relies on projectile impact to create high pressure; such systems are capable of forcing liquid hydrogen into a metallic state.

Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.

Transitional ballistics

Transitional ballistics, also known as intermediate ballistics, is the study of a projectile's behavior from the time it leaves the muzzle until the pressure behind the projectile is equalized, so it lies between internal ballistics and external ballistics.

Gun Ranged weapon that shoots projectiles

A gun is a ranged weapon designed to use a shooting tube to launch typically solid projectiles, but can also project pressurized liquid, gas or even charged particles. Solid projectiles may be free-flying or tethered. A large-caliber gun is also referred to as a cannon.

Caliber (artillery)

In artillery, caliber or calibre is the internal diameter of a gun barrel, or - by extension - a relative measure of the barrel length.

.300 AAC Blackout Rifle cartridge originally designed for use in the M4 carbine

The .300 AAC Blackout, 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. Its purpose is to achieve ballistics similar to the 7.62×39mm cartridge, or even more similarly, the 7.92×33mm Kurz cartridge in an M4 while using standard M4 magazines at their normal capacities. 300 BLK ammunition cannot be used in a rifle chambered for 7.62×40mm Wilson Tactical. It is mainly derived from the .300 Whisper concept, but differs in having been submitted to the SAAMI.

The .276 Enfield (7×60mm) was an experimental rebated rim bottlenecked centerfire military rifle cartridge developed in conjunction with the Pattern 1913 Enfield (P'13) rifle. Development was discontinued by the onset of World War I.

References

  1. https://www.thefreedictionary.com/muzzle+velocity muzzle velocity. (n.d.) Dictionary of Military and Associated Terms. (2005). Retrieved February 15 2020 from https://www.thefreedictionary.com/muzzle+velocity
  2. "Muzzle Velocity". Archived from the original on 15 May 2010. Retrieved 9 June 2011.
  3. "The Accuracy of Black Powder Muskets" (PDF). Retrieved 9 June 2011.
  4. "Speed of a Bullet" . Retrieved 10 December 2013.
  5. "120mm Tank Gun KE Ammunition". Archived from the original on 6 January 2010. Retrieved 9 June 2011.
  6. "Remote Hypervelocity Test Laboratory". Archived from the original on 30 July 2014. Retrieved 29 July 2014.
  7. Brown, Malcolm. "Fastest Gun on Earth: Goals Go Beyond Planet". www.nytimes.com. NY Times. Retrieved 23 March 2018.
  8. 1 2 "The Rifle Barrel" . Retrieved 9 June 2011.
  9. Mizokami, Kyle (7 March 2018). "How guns work" . Retrieved 28 April 2019.
  10. "Rail Strike". The Economist . 9 May 2015. Archived from the original on 17 May 2015. Retrieved 28 April 2019.
  11. 1 2 Government of Western Australia (January 2018). "Storage of explosives" (PDF). Department of Mines, Industry Regulation and Safety. Retrieved 28 April 2019.
  12. "Dictionary of United States Army Terms" (PDF).