Very-low-drag bullet
Encyclopedia
Very-low-drag bullets are primarily a small arms
ballistic
s development of the 1980s–1990s, driven by shooters' desire for bullets that will give a higher degree of accuracy and kinetic
efficiency, especially at extended ranges. To achieve this the projectile must minimize air resistance in flight. Demand has been greatest from target shooters, including benchrest
competitors, but hunters have also benefited. Most VLD bullets are used in rifles.
Bullets with a lower drag coefficient
decelerate less rapidly. A low drag coefficient flattens the projectile's trajectory
somewhat at long ranges and also markedly decreases the lateral drift caused by crosswinds. The higher impact velocity of bullets with high ballistic coefficients means they retain more kinetic energy
.
The resulting projectile should be very "slippery" (well streamlined
) for easier passage through the air. Consistency in bullet production, allied to consistency in the assembly of cartridges
(quality control
) should give excellent shot-to-shot consistency.
The principles of bullet design and flight are classically set out in F.W. Mann's The Bullet's Flight From Powder to Target: Ballistics of Small Arms.
, oxygen free copper
and other highly machinable alloys of copper
, nickel
,and tellurium. These materials are also popular because (aside from tellurium) they are nontoxic, improving the quality of hunted meat, and the health of hunters and their dogs.
Producing accurate bullets this way is not easy. To guarantee consistency and hence accuracy professional quality control during and after production is needed. Mono-metal solid bullets are more expensive than traditional jacketed Hollow Point Boat Tail VLD bullets. Machined mono-metal bullets offer bullet designers the freedom to design slender aerodynamically efficient bullet shapes that can not be produced with more traditional bullet production methods.
Small arms
Small arms is a term of art used by armed forces to denote infantry weapons an individual soldier may carry. The description is usually limited to revolvers, pistols, submachine guns, carbines, assault rifles, battle rifles, multiple barrel firearms, sniper rifles, squad automatic weapons, light...
ballistic
External ballistics
External ballistics is the part of the science of ballistics that deals with the behaviour of a non-powered projectile in flight. External ballistics is frequently associated with firearms, and deals with the behaviour of the bullet after it exits the barrel and before it hits the target.-Forces...
s development of the 1980s–1990s, driven by shooters' desire for bullets that will give a higher degree of accuracy and kinetic
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
efficiency, especially at extended ranges. To achieve this the projectile must minimize air resistance in flight. Demand has been greatest from target shooters, including benchrest
Benchrest shooting
Benchrest shooting is a sport in which very accurate and precise rifles are shot at paper targets from a rest or bench from a sitting position. Benchrest shooters are notoriously detail-oriented and constantly trying to further the accuracy potential of the rifle through experimentation. Nearly...
competitors, but hunters have also benefited. Most VLD bullets are used in rifles.
Bullets with a lower drag coefficient
Drag coefficient
In fluid dynamics, the drag coefficient 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 equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
decelerate less rapidly. A low drag coefficient flattens the projectile's trajectory
Trajectory
A trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...
somewhat at long ranges and also markedly decreases the lateral drift caused by crosswinds. The higher impact velocity of bullets with high ballistic coefficients means they retain more kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
.
Development
The development of VLD bullets has focused on the following main factors:- the production of bullets with concentric and coincident centres of form and centres of mass
- bullet design incorporating a secantSecantSecant is a term in mathematics. It comes from the Latin secare . It can refer to:* a secant line, in geometry* the secant variety, in algebraic geometry...
ogiveOgiveAn ogive is the roundly tapered end of a two-dimensional or three-dimensional object.-Applied physical science and engineering:In ballistics or aerodynamics, an ogive is a pointed, curved surface mainly used to form the approximately streamlined nose of a bullet or other projectile.The traditional...
, tangentTangentIn geometry, the tangent line to a plane curve at a given point is the straight line that "just touches" the curve at that point. More precisely, a straight line is said to be a tangent of a curve at a point on the curve if the line passes through the point on the curve and has slope where f...
ogive, Von Kármán ogive or Sears-HaackSears-Haack bodyThe Sears–Haack body is the aerodynamic body shape with the lowest theoretical wave drag. Aircraft designed to operate at high subsonic or supersonic speeds have their cross-sectional areas designed to match as closely as possible the proportions of Sears-Haack body.By Whitcomb's area rule, the...
profile in the bullet's nose area - the use of carefully tapered bullet heels, or boat-tails
- a cavity or hollow in the bullet nose (hollow point) to shift the projectile's centre of gravity rearwards
- To reduce damage to the bullets' aerodynamics, many modern VLD bullets are bore-riding bullets, in which thin "drive bands" are the only parts that are etched by the barrel's lands. To use these correctly requires bullets and barrels to be precision-fitted to each other.
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
) for easier passage through the air. Consistency in bullet production, allied to consistency in the assembly of cartridges
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
(quality control
Quality control
Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...
) should give excellent shot-to-shot consistency.
The principles of bullet design and flight are classically set out in F.W. Mann's The Bullet's Flight From Powder to Target: Ballistics of Small Arms.
Modern design
VLD bullets are normally machined from solid bars of highly-machinable metals using CNC lathes. Common materials include UNS C36000 Free-Cutting BrassBrass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
, oxygen free copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
and other highly machinable alloys of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
,and tellurium. These materials are also popular because (aside from tellurium) they are nontoxic, improving the quality of hunted meat, and the health of hunters and their dogs.
Producing accurate bullets this way is not easy. To guarantee consistency and hence accuracy professional quality control during and after production is needed. Mono-metal solid bullets are more expensive than traditional jacketed Hollow Point Boat Tail VLD bullets. Machined mono-metal bullets offer bullet designers the freedom to design slender aerodynamically efficient bullet shapes that can not be produced with more traditional bullet production methods.
See also
- Drag (physics)Drag (physics)In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
- Parasitic dragParasitic dragParasitic drag is drag caused by moving a solid object through a fluid medium . Parasitic drag is made up of many components, the most prominent being form drag...
- Boundary layerBoundary layerIn physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of a bounding surface where effects of viscosity of the fluid are considered in detail. In the Earth's atmosphere, the planetary boundary layer is the air layer near the ground affected by diurnal...
- Drag coefficientDrag coefficientIn fluid dynamics, the drag coefficient 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 equation, where a lower drag coefficient indicates the object will have less aerodynamic or...
- Ballistic coefficientBallistic coefficientIn ballistics, the ballistic coefficient 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. BC is a function of mass, diameter, and drag coefficient...
- Nose cone designNose cone designGiven the problem of the aerodynamic design of the nose cone section of any vehicle or body meant to travel through a compressible fluid medium , an important problem is the determination of the nose cone geometrical shape for optimum performance...
- Rob FurlongRob FurlongRob Furlong , is a former corporal of the Canadian Forces, who held the record for the longest confirmed sniper kill in combat, at 2,430 metres...