On behalf of "JBM Small Arms Ballistics" and "Applied Ballistics, LLC" I would like to announce the addition of measured BC data to the JBM bullet library.
For those who are not familiar with the free JBM online ballistics calculators, this is an excellent resource for making accurate trajectory predictions as well as calculations involving stability, recoil, max range, etc.
When calculating trajectories, users can either enter a numeric BC value manually, or select a bullet from the drop down menu. Until recently, the drop down menu would use the BC that's advertised by the manufacturer. Advertised BCs may or may not be accurate for any number of reasons. Now, the bullet library includes the BCs measured by Applied Ballistics, LLC (Bryan Litz) which are referenced to the G7 standard, and are accurate within +/- 1%.
to read about G7 referenced BCs.
The bullets in the JBM library that use the measured BCs are designated "Litz", as shown in the following graphic. When you select these bullets, the program automatically loads the measured BC for that bullet. Just take care in entering all the other inputs accurately, and the program will output a very precise trajectory.
The numeric BC values of the bullets in the library are not visible to the user. If you want to know the numeric BC values, they're published in the book: " Applied Ballistics For Long Range Shooting
" for over 175 long range bullets of all brands, from .22 thru .338 caliber.
Here are some links to the information on the JBM site which explains the new addition in greater detail:
This marriage of accurate data with accurate software will make it easier for shooters to calculate reliable trajectories. You no longer have to get the measured BCs from one place, then go somewhere else to use them; it's all tied together now.