Doppler Radar B.C.

Most people know of Doppler radar from weather stations tracking storms and from police speed radar, but Doppler radar can also be used to track a bullet after it's fired from a gun. The ability for Doppler radar to track a bullet in this way results in the most accurate measurement of a bullet's flight characteristics of any method yet devised. The disadvantage of using Doppler radar is the cost of the radar equipment and complex computer processing needed to make the raw radar data usable. While commonly used for military testing, Doppler radar has been too expensive for most manufactures of sporting bullets to use.

The company Nammo Lapua Oy of Finland (Lapua) has pioneered the use of Doppler radar in measuring the ballistic characteristics of many of their sporting bullets. The result of measuring a particular model of bullet with Doppler radar is the production of a drag function specific to that bullet model. In effect, the actual bullet becomes its own standard by which it's measured, and thus, has a ballistic coefficient of 1.000 at all velocities. While that's great for predicting downrange data, what's lost is the ability to compare that bullet with other bullets relative to industry standards such as G1 or G7. To allow for comparison of their bullets, Lapua also publishes the equivalent G1 and often the equivalent G7 BC values as well as including the bullet specific drag function in commercial software they promote.

When you see the Doppler label in the Bullet library it means we have calculated the G1 and G7 values using the muzzle velocity and time of flight method out to a range of 1000 yards in most cases using an appropriate muzzle velocity for that bullet. We matched the time of flight to the output of the commercial software Lapua promotes where it's using the bullet's specific Doppler drag function. Our G1 and G7 values are different than those published by Lapua, which are based on the muzzle and 100 yard velocities.

In his July 2007 Shooting Times article Dr. Ken Oehler showed the importance of measure BC over long range and the muzzle velocity and time of flight method results in BC values that best match the trajectory of the bullet. Thus, our G1 and G7 values produce drop values that are within 0.5 MOA of those of the Doppler drag function out to ranges of 1000 yards and often more.

see Drag Table Information

see Drag Coefficient Tables