Airsoft pellets (known as BBs) are spherical projectiles used by airsoft guns. Typically made of plastic,[1] they usually measure around in diameter (though selective models use 8 mm), and weigh 0.2-, with the most common weights being 0.20 g and 0.25 g, while 0.28 g, 0.30 g, 0.32 g and 0.40 g BBs are also commonplace. Though frequently referred to as "BBs" among airsoft users, these BBs are not the same as either of the 4.5 mm metal projectiles that BB guns fire,[2] or the 0.18abbr=onNaNabbr=on-sized birdshot from which the term "BB" originated.[3]
Although the majority of pellets bought and used are simple spherical projectiles made of plastic, some of the following special varieties can be used to give a player an advantage, such as higher quality pellets.
Biodegradable pellets are available, and are often required by outdoor fields where sweeping is not an option. Conventional pellets pollute the environment, as most non-biodegradable pellets have a mineral or petroleum-based center, coated in non-biodegradable plastics, thus ensuring they will stay in the environment for several hundred years if not collected. Biodegradable pellets are made of various types of resin, often developed for the agricultural industry, and better makes are certified as compostable. Commonly used plastic resins include polylactic acid or polylactide (PLA) which is based on renewable materials like corn products and a molecular formula of (C3H4O2)n.[4] There is a mixture of degradable processes being used, such as soil microbes and photosensitive degradation. Biodegradable pellets are currently being produced with all the characteristics of the best of the conventional, with homogeneous resin construction.
Most high-quality pellets are available in a non-biodegradable version, as well as a biodegradable version that costs slightly more. Both bio- and non-biodegradable pellets are popular and widely available.
Glow-in-the-dark pellets, known as tracer pellets, can be used in conjunction with a device that "charges" the pellets by flashing them with a burst of light before 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, or is included inside the magazine or hop-up unit. There are also biodegradable tracer pellets available.
This type of pellet is dark-colored so that the opponent has a tougher time spotting the pellets' origin, as the most common pellet color is white, which makes it easy for the opposition to spot the shooter by following the trail of pellets. Two major problems of this variant of pellet are that there are few high-quality pellets in this color and the shooter has a difficult time seeing their own trail of shots.[5]
Paint-filled pellets are also available, called "paintballs", which are very similar to those used in 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 feeding systems, such as high capacity magazines, for the same reason. With some companies, the use of paintballs voids the airsoft gun's warranty; paint may get into the mechanical workings of the airsoft gun and damage parts beyond simple maintenance. These issues may be fixed by removing the hop-up unit, which can void the warranty, and also switching to a low or mid-capacity magazine with no mechanized feed.
A specialized pellet coated in a powder that leaves a small colored mark when it strikes a surface. The powder deposits from these pellets are left in any part of the airsoft gun or storage unit that the pellet comes in contact with; build-up over time, without cleaning, can cause malfunctions or damage to moving parts.[6]
Made from 100% silica, the material in these pellets is very evenly distributed, improving flight characteristics. Some accounts indicate that these pellets are capable of breaking glass and industry-standard protective eyewears. Due to safety concerns and reports of injuries caused by this type of pellets,[6] it is commonly prohibited in professional airsoft facilities.
Metal pellets are also marketed for use in airsoft guns. These pellets are heavier and harder than conventional polymer pellets, and the impact from a metal pellet can injure players. Safety concerns make metallic pellets suitable only for target shooting. The added weight reduces the effect of crosswind on the pellet, imparting more accuracy when fired at longer ranges in outdoor environments where wind would significantly alter the trajectory of traditional pellets. Many airsoft locations where players can pay to play against others prohibit the use of metallic pellets due to the fact they are more likely to penetrate skin. Metallic pellets are mostly used in a standard pump-action or carbon dioxide-powered BB guns.
Created from laboratory-grown crystal lattice structures, these pellets are individually machined to precise specifications that ensure uniform weight, dimensions and surface shape. This precision and uniformity provides ideal ballistic performance and consistent flight patterns. The manufacturing process and materials are much more costly than molded polymer pellets – as a result, ceramic pellets are considerably more expensive than standard airsoft pellets. The material is able to defeat standard eye protection due to the weight and higher energy required to propel it, thus unsuitable for use against other human targets
Translucent pellets come in many colors. They tend to be non-biodegradeable and it can be difficult to find high quality versions compared to their opaque counterparts.
Pellet mass is an important factor when choosing pellets. The pellet's mass influences several aspects of pellet performance:
A player's choice of pellet mass is governed by their gaming style (assaulting vs. sniping), the airsoft gun used (internal parts), game venue condition (in/outdoor) and size, and muzzle velocity regulations.
Also, the quality of the individual pellets may influence choice of price-range or manufacturer. Low-cost pellets are often considered to have such negative characteristics as residual plastic from the moulding process (flash); lower impact resistance and some deviation from perfect spherical shape. Cheaper pellets are known to shatter when fired, which can cause irreparable damage to the internals of the gun. Higher cost BBs generally have a smoother finish, are more impact resistant and are perfectly spherical.
6 mm is the industrial standard size used in almost all spring, electric and gas airsoft guns. A wide variety of pellet masses are also available for different usages.
8 mm pellets are most commonly used in gas-powered airsoft shotguns with high velocities.
The pellet speed of spring-powered and automatic electric guns is determined in large part by the tension of the gun's main spring. Muzzle velocity limits are between 90and for AEGs and 120to(-) for single-shot spring sniper rifles.[12]
For comparison purposes, is the typical mass of a paintball pellet, and is the standard for an airsoft pellet. At 3 g mass, a pellet flying at 100m/s has 15 J of kinetic energy, while a 0.20 g has 1 J. It is important to distinguish that, in airsoft, the terminal impact energy is very close to the kinetic energy of the pellet because the collision is almost completely elastic. On the other hand, in paintball, the pellet fractures upon impact, leading to an inelastic collision with energy loss, and thus the impact energy is smaller than the kinetic energy of the pellet. Nevertheless, the typical impact energies of the airsoft pellet tend to be much smaller than of the paintball.
While a pellet's muzzle velocity is important for safety proposes, it will lose velocity during flight due to drag. The typical deceleration of a pellet of mass "m" and diameter "D" is given by the quadratic drag:
Adrag=
| 1 | |
| 2m |
\rhoairv2 ⋅ 0.47 ⋅ \pi\left(
| D | |
| 2 |
\right)2
where v is the instantaneous velocity of the pellet. For typical values of the pellet (m = 0.2 g, v = 120 m/s, D = 6 mm), the drag can be very high (
576 m/s2
The above equation has a simple solution for velocity vs. distance:
v=
| -s/{s0 | |
| {v | |
| 0}{e |
where
{v0}
s
{s0}
1/e
{v0}
{{s}0
In particular, for typical values and neglecting wind effects or hop-up usage, a straight shot from a height of 1.8m (05.9feet) has a range of . On ground hit, the impact energy of the pellet is 0.1 J. However, the same shot at close quarters (e.g. 5 m distance) has an impact energy of 1 J (see figure).
Airsoft pellets travelling with sufficient velocity can leave small superficial wounds when hitting exposed skin. While this can be painful, these wounds are typically closed contusions and heal quickly without needing any medical attention. However, pellets can cause more serious damage to the more vulnerable parts of the body, such as the eyes and ears. Lower protective face masks are recommended during airsoft matches to shield players' nose, mouth, teeth and ears, and goggles or other protective eyewear are mandatory for eye protection.
The critical velocity required for skin penetration can be calculated using the formula:
vcr=162.1e-0.38
where m is the mass of a spherical bullet, in grams. Penetration is defined here as entering the skin to a depth of more than half of the spherical pellet's diameter.
Accordingly, a typical 0.20 g airsoft pellet will penetrate the skin at 136.7m/s. Because many high-end AEGs, spring- and gas-powered airsoft guns can achieve such velocity at close ranges, many airsoft venues set strict limits on the maximum muzzle velocities allowed on the field, requiring each player to undergo a chronograph test prior to participating in a game. Some venues even have restrictions on minimal engagement distances, where shooting at opponents nearer than a set distance is prohibited, and a "bang bang" rule (players imitate firing by shouting "bang bang" instead of really firing the weapon) is often implemented.
The following excerpts from the United Kingdom Parliament's "Principles of Firearms Control"[13] 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". 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. 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·lbs) or joules (J)."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". 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). 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, 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."
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 |