I've found the Point Blankprogram to be quite accurate and it includes a function to calculate the BC of a bullet using weight and velocities at muzzle and 100 yards. It is located at www.HuntingNut.comand it's free. It is easy to download and can be put on a thumb drive and carried around with you if you work with multiple computers. I use it for doing comparisons similar to what Chap is doing. It also comes in handy to bust some of the myths that seem to presist about certain ultra long range muzzleloaders out there not to mention the CF comparisons.