The best ballistics calculators, the ones that used to be on the Border Barrels website, are now on the author, Geoffrey Kolbe's, own website....

http://www.geoffrey-kolbe.com/external_ballistics.htm

The Drag Curve calculator and the Barrel Twist calculator are hugely useful for examining potential bullet designs, and I used them exclusively when designing Bob's Boattails.... They are based on Robert McCoy's McDrag and McGyro programs.... and produce the output in graphical format....

Bob