The .30-06 Springfield (pronounced thirty-aut-six) or just 06 (aut-six) for short, was developed by the Springfield Armory for the U.S. Military in 1906. The numerical designation was caliber first, .30 (as was normal) and year developed second -06, because there were many different .30 caliber designs in the late 1800’s and early 1900’s. The metric notation for this cartridge is 7.62x63mm.