I know some folk use this software. An updated version is now available at a small cost.
On Target Precision Calculator
OnTarget Precision Calculator v2.10 comes with a fully functional 15 day free trial. During the free trial click the Try button in the initial splash screen to start using the program.
The registration fee for the OnTarget Precision Calculator v2.10 is $14.99. We are running a special introductory price of $11.99 through March 31, 2011.
Initial impressions are good.