Shortly after the end of World War I, the U.S. Ordnance Corps began looking for a smaller cartridge to replace the 30-06 Springfield. With typical government efficiency, the quest was still being pursued toward the end of the Second World War. By 1944, engineers at Frankford Arsenal had begun to exp...

Infinity is an exterior ballistics program for small arms. Infinity Suite includes the Infinity exterior ballistics program, additional Reloading Data programs to calculate all the cartridge and reloading data included in the 5th Edition printed manuals, and the Reference materials from the 5th Edition printed manuals. Infinity is the sixth version of the Sierra Bullets exterior ballistics program.

The concept of metal-cased, or “fixed” ammunition is actually a relatively recent development. First produced in viable forms in the early 1850s, today’s modern cartridge has its roots in the .22 Short Rimfire. The idea of a “cartridge,” however, is by no means new. The use of pre-measured charges of gun powder and bullet rolled into paper cartridges is believed to date back to the early 1600s, when King Gustavus Aldophus of Sweden ordered his soldiers to carry their ammunition in this manner. In fact, the word “cartridge,” is derived from the Latin word for paper, charta.

There are at least three ways to describe the BC. First, it is widely recognized as a figure of merit for a bullet’s ballistic efficiency. That is, if a bullet has a high BC, then it will retain its velocity better as it flies downrange from the muzzle, will resist the wind better, and will “shoot flatter.” But this description is qualitative, rather than quantitative. For example, if we compare two bullets and one has a BC 25% higher than the other, how much is the improvement in bullet ballistic performance? This question can be answered only by calculating the trajectories for the two bullets and then comparing velocity, wind deflection, and drop or bullet path height versus range from the muzzle.