Airsoft pellets
From Wikipedia, the free encyclopedia
Airsoft pellets are spherical projectiles used in Airsoft models. Typically made of plastic, they typically range in size from 5.98 to 6.00 mm in diameter, though some long range models use 8 mm pellets. Often called "BBs", after the ammunition for BB guns, this is a misnomer; true BBs are named for BB sized shotgun shot, which is 0.177 inches (4.5 mm) in diameter, which is 25% smaller than an airsoft pellet.
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[edit] Composition
In addition to (crude oil derived) plastic, starch-based biodegradable plastic, metal or graphite-coated and solid-steel pellets are also available. Pellets are most commonly found in white and yellow, but since the plastics most commonly used are readily colored, many other colors are produced. Such colors include green, blue, orange, gold, red, and phosphorescent colors. Non-plastic pellets are generally the color of the material used for the exterior of the pellet.
[edit] Varieties of pellets
[edit] Biodegradable
Biodegradable are available, and are often required by outdoor fields. They are made of starch-based plastic. Many times, pellets marked "biodegradable" are little more than two halves of a regular pellet than are held together by biodegradable material. Biodegradable pellets are not as strong as their plastic counterparts, and therefore they shatter easier. These types of BB's are only manufactured by a handful of companies.
[edit] Tracers
Glow-in-the-dark pellets, known colloquially as tracer, can be used in conjunction with a device that "charges" the pellets by flashing them with a burst of visible light on leaving the barrel, so that they remain luminescent in flight for use during nocturnal games/operations. This tracer unit is usually hidden from view, often disguised as a suppressor (silencer). There are also biodegradable tracers available
[edit] Non-spherical pellets
There have also been airsoft models that use non-spherical pellets. The best known of these is the Asahi "Blade Bullet", which are now extremely difficult to find and quite expensive to buy. These were designed to be shot from the short-lived Asahi M700 and M40 premium grade rifles, which were produced in 1993. Compatibility with other airsoft guns is highly limited, especially due to their incompatibility with hop-up features.
[edit] Paintballs
Paint-filled pellets are also available, which are very similar to those used by paintball. Airsoft models equipped with the hop-up projectile stabilizing system are not able to use these, as the thin shells are liable to break in the barrel, soiling it with paint. These special pellets are also incompatible with Airsoft models using mechanized feed systems, such as clockwork magazines, for the same reason. Paintballs generally are bad for the gun and often cause jams or other internal problems. With some companies, the use of paintballs voids the airsoft gun's warranty.
[edit] Proprietary pellets
Also, during the early 1980s, most airsoft makers used their own proprietary pellets. Companies such as Masudaya and tradeMark Airguns had varieties of ammo, such as the flat-headed "Long Range" ammo used in the Masudaya Bolt series, or the soft rubber conical pellets used in the tradeMark Falcon-077.[citation needed]
[edit] Pellet weights
Heavier pellets retain velocity better than lighter weight pellets, but require a more powerful gun. In guns with adjustable power, such as a gas gun, a lighter pellet can give more shots per charge than a heavy pellet, but with a corresponding loss in range. Heavier pellets retain their velocity better due to higher sectional density (see external ballistics) but will have a lower muzzle velocity and a more curved trajectory.
6 mm pellet weights and their usage
- 0.12 g - Used by some gas and spring, and electric weapons. High velocity and low stability. Not to be used in high end AEGs such as Tokyo Marui and Classic Army
- 0.15 g - Same uses as 0.12 g. Uncommon. Not to be used in high end AEGs such as Tokyo Marui and Classic Army
- 0.20 g - Standard weight for most weapons. AEGs use these or slightly heavier pellets.
- 0.23 g - Heavier pellets for AEGs. Blends speed of 0.20 g with range and accuracy of 0.25 g. Made popular by Tsunami Airsoft.
- 0.24 g - An oddity. Only known manufacterers are Airstrike (a subsidiary of Daisy) and Crosman.
- 0.25 g - Heaviest weight for standard AEGs, blowback and spring guns. Tokyo Marui standard AEG, gas, and spring guns are set at the factory for 0.25 gram BB's, and they usually include a package of 200 of these with the gun.
- 0.28 g - For highly upgraded AEGs or sniper rifles. Significantly cheaper than 0.30 g but yields similar performance
- 0.29 g - Maruzen Super Grandmaster BBs, designed for their Air Precision Shooting series of guns. One of the most precisely ground and accurate BBs available[verification needed], but cost more than other alternatives.
- 0.30 g - Standard weight for most sniper rifles. Western Arms pellets for their gas blowback pistol series. Uncommon.
- 0.36 g - Heavier pellets for sniper rifles. Very slow but have high stability.
- 0.43 g - For the highest level of upgrades in spring and gas sniper rifles. Usually graphite coated.
- 0.88 g - Possibly the heaviest type of BB available. Usually made of steel and comes with a polished finish. Rarely used and often hard to find. Can only be used on extremely high power (usually CO2 based) guns, such as classic airsoft guns.
8 mm pellet weights
- 0.27 g - Low weight
- 0.34g (Normal)- Standard weight
- 0.35g (Biodegradable)- Standard weight
- 0.45 g - Heaviest weight
[edit] Pellet ballistics
[edit] Pellet velocity, energy and weight
The pellet velocity of automatic electric guns is determined in large part by the tension of their main spring and so there tends to be a stratification of values. The most common airsoft velocity limits are between 200 to 300 ft/s for AEGs and 300 to 450 ft/s for single shot guns (sniper rifles). Below are some common speeds of airsoft pellets.
- As for comparison purposes, 3.00 g is the typical weight for a paintball pellet. At this weight a pellet flying at 90 m/s results in 12.54 J and 14.99 J for 100 m/s. Such energy levels and weight are not used on Airsoft, but comparing them with airsoft energy levels is useful to show the presence of different collisions in these sports. Higher energy but different collisions read Elastic collisions (airsoft) and Inelastic collisions (paintball) topics for further information.
- Red line in speed vs energy image is the usual Crony (chronograph) weight for 6 mm (0.20 g).
[edit] Dangers to humans
Airsoft pellets typically leave small welts on human targets. While mildly painful, pellets are not especially damaging to the skin. Eye protection is universally required to prevent damage to eyes. It is also often recommended that full face masks be used during airsoft matches to protect the players' teeth and ears. On very some occasions players have had teeth chipped or knocked out or ears injured by a pellet.
Although there have been no documented cases in airsoft, there is a possible hazard when dealing with graphite-coated pellets. In the early days of paintball some players would coat their rounds with graphite so that they would feed into the gun better. Players started to find that if any rounds broke the skin the wound would not properly heal, leaving a scar. Players and field owners should be aware that this problem may exist in the realm of airsoft as well.
The following excerpts are from the United Kingdom Parliament's "Principles of firearms control", Home Affairs Select Committee Second Report, 6 April 2000, expound on the level of danger involved with low-energy projectiles:
"25. The Firearms Act 1968 defines a firearm "a lethal barreled weapon of any description from which any shot, bullet or other :missile can be discharged".[51] In this context, a "lethal weapon" means a weapon capable of firing a projectile with sufficient :force to inflict more than a trivial injury, i.e. with a force sufficient to puncture the skin.[52] The force with which a firearm :is able to deliver a projectile is normally expressed in terms of the kinetic energy it generates at its muzzle—the "muzzle energy". :This energy is normally expressed in units of foot-pounds (ft·lbf) or joules (J).[53]
"26. The Home Office and the Forensic Science Service considers that the lowest level of muzzle energy capable of inflicting a penetrating wound is one foot pound force (1.35 J): below these power levels, weapons are "incapable of penetrating even vulnerable parts of the body, such as the eye".[54] However, more recent analysis by the Forensic Science Agency for Northern Ireland has indicated that a more reasonable assessment of the minimum muzzle energy required to inflict a penetrating wound lies between 2.2 and 3.0 ft·lbf (3 to 4 J).[55] We will deal more fully with this discrepancy at paragraphs 123 to 130 below."
"123. The power level at and above which an air weapon is considered a firearm in law is presently set at 1 ft·lbf. However, we note above that the Forensic Science Agency of Northern Ireland has more recently assessed the power level at which a barreled weapon is capable of inflicting a lethal wound as between 2.2 and 3 ft·lbf, and the Secretary of State for Northern Ireland has proposed that the law relating to firearms in Northern Ireland be amended to take this into account.[201]"
On another document also regarding firearms, "The Eleventh Annual Report of the Firearms Consultative Committee", the penetration levels lies between 2 and 3 J based on a research for US Army and DiMaio's work in "Minimal Velocities Necessary for Perforation of Skin by Air Pellets and Bullets, Journal of Forensic Sciences".
| Date | Reference | Energy level | Observations | |
| April 2000 | Principles of firearms control [paragraph 26],Home Office and the Forensic Science Service; | 1,35J | penetrating wound (later changed by paragraph 123, see below) | |
| April 2000 | Principles of firearms control [paragraph 123], Forensic Science Agency for Northern Ireland; | 3,00J~4,00J | penetrating[26]/lethal[123] wound | |
| March 2002 | The Eleventh Annual Report of the Firearms Consultative Committee DiMaio's work in Minimal Velocities Necessary for Perforation of Skin by Air Pellets and Bullets,Journal of Forensic Sciences; | 2,00J~3,00J | penetration level |
[edit] Hop-up & Bernoulli's principle
The term Hop-up describes the back-spin put on airsoft pellets and BB's to increase their range and (vertical) accuracy via Bernoulli's principle. Hop-up acts somewhat like the rifling on the barrel of a firearm, but without the increase in horizontal accuracy. Also, being light-weight, airsoft pellets are still affected by wind when fired.
Airsoft hop-up devices apply a backspin to the pellet so that the pressure force acts on the pellet opposite to the direction that gravity is pulling it. This causes the pellet to fall less over a given distance than it would without the spin applied to it.
In airsoft guns this is often implemented as a rubber piece at the rear of the barrel that is thicker at the top of the barrel than the bottom. As the pellet moves past this piece it tends to roll, inducing a backspin. This is usually adjustable so that the effect can be tuned to suit the weight or speed of the pellet, and each player's preference.
Bernoulli's principle as applied to an airsoft pellet is as follows. As a spinless spherical pellet flies along its trajectory through the air (the air being the "fluid" in this case) the pressures on all sides of the pellet are equal because the air is traveling the same velocity relative to the surface of the pellet. If a spin is applied to the pellet about an axis perpendicular to the velocity vector (for example a backspin) the air will be rushing slower (relative to the pellet surface) on the side that is spinning away from the velocity vector and faster on the side that is spinning towards the velocity vector. Bernoulli's principle says this difference in fluid velocity implies a difference in pressures, which is a force that will cause the pellet to move in a direction perpendicular to the velocity vector.
Another cause of the apparent lift on an airsoft pellet is the Magnus effect. There is a layer of non-moving air on the surface of the pellet (boundary layer). This is why a golf ball has dimples; this layer acts like ball bearings. In the case of a spinning ball, this layer gets thrown off at an angle. Newton's laws say that in order for air to be thrown in one direction, the ball has to move in the other direction. According to the Magnus explanation, the rotating ball would throw air downward and to the rear, thus giving lift. The air on the bottom of the ball is slowed down, so when the separated air comes back together, it is lower than the middle of the ball, appearing like a comet's tail pointing down. This can be verified in wind tunnels and is very well documented in fluid dynamics textbooks.
[edit] Airsoft Pellet Manufacturers
China
- FiDragon
- CYMA
Japanese
- Excel
- Maruzen
- Tokyo Marui
Taiwanese
UK
- UKARMS
