The Effective Firearms Guide to Stopping Power calculates up to seven (7) indices of bullet performance. For a visual example, please view the YouTube tutorial: https://www.youtube.com/watch?v=SZm-4Zc-qlo Enter a muzzle velocity (feet per second) and bullet weight (grains) and it can display the bullet momentum, the muzzle (kinetic) energy, and the Matunas Optimum Game Weight (OGW). If you are checking a frangible varmint bullet, then the (V) checkbox can be set as the OGW uses a different constant factor for varmint loads." Enter the caliber and you can also display the Taylor Knock Out Factor (TKOF) and the Thorniley Stopping Power. If you also enter bullet form, the Hatcher Relative Stopping Power value is also available (with the expanded value for hollow/soft point). While all seven values are available via the Internet, obtaining them would require visiting multiple web sites, which can be awkward while standing in a store evaluating ammunition options on the shelf. Please send any questions, complaints, or corrections to info@SecurityMediaServices.com.