For SIGSHR and Scorch. . . . . .
Here's the history of the 7.62 NATO round's development and its commercial equal, the .308 Winchester:
http://riflemansjournal.blogspot.com...in-of-308.html
Note that in 1944 Springfield Armory was instructed to develop the new weapon (eventually the M14) and Frankford Arsenal to develop the cartridge (eventually, the 7.62x51mm NATO).