Very-low-drag bullet

Very-low-drag bullets (VLD) are primarily a small arms ballistics 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 low 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 remaining velocity of bullets with ballistic coefficients at impact also delivers more kinetic energy.

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 secant ogive, tangent ogive, Von Kármán ogive or Sears-Haack 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

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

A collection of modern mono-metal solid VLD bullets can be seen at the [http://www.lehighbullets.com/ Lehigh Bullets & Design] , [http://www.lima-wiederladetechnik.de/Englisch/LM-Class-Bullets.htm LM Class Bullets] and [http://www.gsgroup.co.za/sp.html GS Custom Bullets] websites.Alloys like copper nickel, tellurium copper and brass like highly machinable UNS C36000 Free-Cutting Brass are used for turning these projectiles on precision CNC lathes. 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, when compared to traditional jacketed Hollow Point Boat Tail VLD bullets. Mono-metal bullets offer bullet or projectile designers however more freedom to design CNC lathe machinable slender aerodynamically more efficient bullet shapes that can not be produced with more traditional bullet production methods.

ee also

* Drag (physics)
* Parasitic drag
* Boundary layer
* Drag coefficient
* Ballistic coefficient
* Nose cone design
* Rob Furlong

References

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

External links

* [http://bryanlitz.bravehost.com/BulDes.html General Notes on Bullet Design]
* [http://www.jacksonrifles.com/vldvarmints.htm VLD bullets on long-range varmints]
* [http://www.lima-wiederladetechnik.de/Englisch/Haack_minimum_drag_bullet.htm Haack Minimum Drag Bullet]
* [http://www.lima-wiederladetechnik.de/Ballistik/Lilienthal-139-1-Haack.pdf Geschoßformen kleinsten Wellenwiderstandes by W. Haack, Bericht 139 der Lilienthal-Gesellschaft (1941) de icon]
* [http://www.lima-wiederladetechnik.de/PDF/Kneubuehl.pdf What is the Maximum Length of a spinstabilized Projectile? by Mr. Beat Kneubühl]
* [http://www.lima-wiederladetechnik.de/Englisch/LM-Class-Bullets.htm LM Class Bullets, very high BC bullets for windy long Ranges]
* [http://www.lehighbullets.com/ Lehigh Bullets & Design]