A very-low-drag bullet (VLD) is primarily a

small arms A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...

ballistics development of the 1980s–1990s, driven by the design objective of bullets with higher degrees of accuracy and kinetic efficiency, especially at extended ranges. To achieve this, the projectile must minimize

air resistance In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...

in flight. Usage has been greatest from military

sniper A sniper is a military/paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with high-precision r ...

s and long-range target shooters, including F-class and benchrest competitors, but hunters have also benefited. Most VLD bullets are used in rifles. VLD bullets typically have a

ballistic coefficient In ballistics, the ballistic coefficient (BC, ''C'') of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration: a high number indicates a low negative acceleration—the ...

greater than 0.5, although the threshold is undefined. Bullets with a lower

drag coefficient In fluid dynamics, the drag coefficient (commonly denoted as: c_\mathrm, c_x or c_) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag e ...

decelerate less rapidly. A low drag coefficient flattens the projectile's

trajectory A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete tr ...

and also markedly decreases the lateral drift caused by crosswinds. The higher velocity of bullets with low drag coefficients means they retain more kinetic energy.

Development

VLD bullets are long and heavy for their diameter, to achieve a high

sectional density Sectional density (often abbreviated SD) is the ratio of an object's mass to its cross sectional area with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis. Secti ...

. Development of VLD bullets has focused on reducing a form factor defined as the sectional density divided by the ballistic coefficient. Form factor can be minimized by: * bullet nose design incorporating a secant ogive, tangent ogive,

Von Kármán ogive Given the problem of the aerodynamic design of the nose cone section of any vehicle or body meant to travel through a compressible fluid medium (such as a rocket or aircraft, missile, shell or bullet), an important problem is the determination o ...

or Sears-Haack profile * the use of tapered bullet heels, also known as boat-tails * a cavity or hollow in the bullet nose (

hollow point upright=0.2, Cross-section of a hollow-point bullet; proportions are those of a .22 Long Rifle cartridge Jacketed soft point (JSP) round. Right: Jacketed hollow-point (JHP) round. JSP is a semi-jacketed round as the jacket does not extend to ...

) to reduce weight while shifting the projectile's

centre of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

rearwards to improve stability with concentric and coincident centre of pressure and

centre of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force may ...

The resulting projectile should be

streamlined Streamlines, streaklines and pathlines are field lines in a fluid flow. They differ only when the flow changes with time, that is, when the flow is not steady. Considering a velocity vector field in three-dimensional space in the framework of ...

for easier passage through the air. Consistency in bullet production, allied to consistency in the assembly of cartridges (

quality control Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "a part of quality management focused on fulfilling quality requirements". This approach place ...

) should give excellent shot-to-shot consistency. The principles of bullet design and flight are classically set out in

Franklin Ware Mann Franklin Weston Mann (July 24, 1856 – November 14, 1916) was an American physician and inventor remembered as author of the pioneering ballistics text entitled ''The Bullet's Flight from Powder to Target: The Internal and External Ballistics of ...

's ''The Bullet's Flight From Powder to Target: Ballistics of Small Arms''.* Mann, F.W.: The Bullet's Flight From Powder to Target: Ballistics of Small Arms (1942 and other reprints)

Mono-metal designs

Machining mono-metal bullets (coreless bullets made of one single metal) offers bullet designers the freedom to design slender, aerodynamically efficient shapes that cannot be produced with more traditional bullet production methods. Professional quality control during and after production is needed to guarantee the bullets' consistency and accuracy. Mono-metal solid bullets are more expensive than traditional jacketed hollow point boat-tail VLD bullets. To reduce damage to the employed

barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...

and increase muzzle velocity, some modern mono-metal VLD bullets are bore-riding bullets, in which thin driving bands are the only parts that are etched by a barrel's lands. The use of driving bands originates from

artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during si ...

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

s and to use these driving bands correctly requires projectiles and barrels to be precision-fitted to each other. Mono-metal VLD bullets are normally machined from solid bars of highly-machinable metals or alloys using CNC lathes. Common materials include UNS C36000 free-cutting

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...

, lead-free brass,Wieland-SW1 lead-free special brass
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oxygen-free copper Oxygen-free copper (OFC) or oxygen-free high thermal conductivity (OFHC) copper is a group of wrought high-conductivity copper alloys that have been electrolytically refined to reduce the level of oxygen to 0.001% or below. Specification Ox ...

and other highly machinable alloys of

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow t ...

, and

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionall ...

References

External links

VLD_bullets_on_long-range_varmint_hunting
.html" ;"title="varmint hunting">VLD bullets on long-range varmint hunting
">varmint hunting">VLD bullets on long-range varmint hunting
{{DEFAULTSORT:Very-Low-Drag Bullet Ballistics Shooting sports equipment Projectiles

Development

Mono-metal designs

See also

References

External links