Many forces act upon a bullet in flight, and as the distance of a shot increases, so too does the influence that these forces can have on a bullet's trajectory. Shooting at close range may not require the shooter to compensate much for these variables, but the further out a shot is taken, the more a rifleman must account for these effects on the projectile. Many will find that for shots made beyond point-blank range, a little computational assistance is appreciated-and for hits on targets at extreme range, can even become essential.
Enter exterior ballistics software programs like Sierra Bullet's Infinity line, now in its seventh version. Infinity 7's ballistics calculator allows users to generate their own customized range cards taking into consideration the specific firearm being used, the particular bullet selected and any environmental conditions like winds, elevation, barometric pressure and temperature.
Infinity 7 allows users to save firearm configurations for multiple guns-which includes data on cartridge chambering, sight height, barrel length, barrel twist rate and more. The program contains bullet information as provided by the manufacturers, but also allows the user to change this data if actual conditions differ from what is advertised on the box. Infinity 7 is highly customizable, allowing users to create range cards with all the information they want-and only the information they want-included.
The program also generates trajectory charts of the calculated data to visually represent bullet path, energy and velocity downrange, and the wind drift. The calculator can run multiple simulations at a time, allowing users to compare the external ballistics of several different loads simultaneously. Other features include twist rate and recoil calculators, and the ability to encrypt and password-protect your data.
Sierra's Infinity 7 Exterior Ballistics Software is compatible with Windows 2000, 7, 8, Vista or XP. A Suite version, which includes the Sierra Bullets 5th Edition Reloading Manual on CD-ROM, is also available. Price: $40, $60 (Suite). Contact Sierra Bullets, 1400 West Henry Street, Sedalia, MO 65301; (888) 223-3006;SierraBullets.com.