The JBM Bullet Library has approximately 2000 bullets from as many manufacturers and sources available. They are arranged by Manufacturer, Caliber (in inches), Weight (in grains) and Description. Bullets are listed in the same way the manufacturer lists them which leads to many different descriptions (e.g. BT, Boattail, SP, Soft Point, etc) but this allows one to find the bullet from the manufacturers data.
It is important to remember that the output of the calculator is only as good as the inputs and one of the key inputs is the drag data. Most of the data comes from manufacturers websites (see BC Links) and consists of the typical G1 ballistic coefficient. These values are either measured or estimated and I believe represent the company's best effort to find the BC.
When other sources of data are made available they are input into the library. These sources have a short indication of the source of data in the description. The two most common are the Lapua CD data and Bryan Litz.
Bryan Litz, the ballistician for Berger Bullets has recently published his book on long range ballistics, Applied Ballistics for Long Range Shooting. This book, among other things, includes software and experimentally measured ballistic coefficients for 175 bullets. The bullets have been added to the JBM Bullet Library using the G7 drag function bullets measured by Bryan are denoted by "(Litz)" in the description. The G7 coefficients should give better calculations than the G1 coefficients over the ranges typically fired in long range shooting. When given the choice of the manufacturer's data or the measured coefficients, I would try Bryan's data.
Lapua has released CD (drag coefficient) as a function of mach number for some of their bullets. This data typically contains over thirty coefficients to model the drag of the bullet. The data for these bullets can be found here toward the bottom of the page. The Lapua bullets in the library that use the CD data have "(CD)" in the description.