The information provided in the bullet data sheets is the result of independent testing by Applied Ballistics. The bullet data sheets provide: dimensioned drawings and geometric information, drag and velocity specific BC measurements, and a stability map for a variety of barrel twists and atmospheric conditions. The data sheets are formatted just like those found in Ballistic Performance of Rifle Bullets 3rd Edition *Coming Summer of 2017*. In that book, you can find similar data sheets for over 730 long range bullets and 90 Rimfire Bullets. Here is a complete list: Complete Bullet List
This sample data sheet below shows all the information available in the data sheets, along with some discussion about what the information means and how to use it.
The dimensioned drawings are useful for several purposes. Obviously they give you an idea of how a bullet is proportioned in relation to other bullets. You can use the dimensional information to design custom chambers to fit a particular bullet. You can also use the bullet dimensions in aerodynamic prediction programs to generate data tables for high level simulations.
The parameters listed below the drawing are self explanatory, perhaps with the exception of the Ogive Radius and Rt/R parameters. Most bullet noses are sections of circular arcs. The Ogive Radius is the radius of the circle used to generate the nose profile. The Rt/R ratio is basically a measure of how aggressive the ogive shape is. An Rt/R ratio of 1.00 would be a perfectly tangent ogive, meaning the nose connects with the bearing surface very smoothly. An Rt/R of 0.5 represents the most aggressive VLD style ogive which has the appearance of an abrupt transition from nose to body. Rt/R values close to 0.5 result in lower drag for the bullet, but also make the bullet more sensitive to seating depth.
The Drag and Ballistic Coefficient data is a complete representation of the bullets flight characteristics over a range of velocities. The bullets drag coefficient as well as it’s G1 and G7 form factors and BC’s are tabulated in 500 fps increments from 3000 down to 1500 fps. This is useful for determining which standard (G1 or G7) is a better fit for the particular bullet. The BC which shows the least amount of variation over the velocity range is the appropriate BC to use. Typically for boat tail bullets, the G7 standard is a better representation.
The Rifling Twist Rate and Stability map shows the gyroscopic stability factor (as calculated by the Miller Twist Rule) for the bullet when fired from various barrel twists in different environmental conditions. Thinner air results in higher stability, and vice versa. The conditions associated with Best, Nominal and Worse case scenarios are as follows:
Best case: 1000 feet altitude, 100% humidity, 100 degrees F, and 3000 fps muzzle velocity.
Nominal case: sea level, 50% humidity, 59 degrees F, and 2800 fps muzzle velocity.
Worse case: sea level, 0% humidity, 0 degrees F, and 2600 fps muzzle velocity.
Of course there are extremes that would exceed the best and worse case, but the point is to demonstrate how much these environmental conditions affect stability.
Rimfire information is scarce, which is surprising for how popular it is. Applied Ballistics has begun an in-depth research project in to Rimfire Ammunition. In the 2nd Edition we added 90 Rimfire Bullets. Along with the Data Sheets found in the Ballistic Performance of Rifle Bullets 2nd Edition, you will also find an in-depth study of Rimfire Ammunition in Modern Advancements in Long Range Shooting Vol 2. Just some of the topics include: Average MV, Standard Deviation of MV, Ballistic Coeffecient referenced to the G1 Standard, Standard Deviation of the G1 BC, Average Performance Through All Barrels, Rimfire Ammo Sorted by Consistency, Consistency of Muzzle Velocities in Relation to the Speed of Sound, Effects of Barrel Length and Twist on Rimfire Ammo Performance, How does the Barrel Length affect Muzzle Velocity, How does the Barrel Length Effect SD of Muzzle Velocity, How does the Twist Rate affect the Average BC, Does the Twist Rate effect the Consistency of BC, and more!