Gentlemen, just for once I am going to jump in and claim superior knowledge, as the one-time holder of 13 patents and engineering advisor to the patent office of a very large international corporation.
There is nothing novel in the sense of patentability in making yet another cartridge distinguished only by mechanical dimensions from a lot of other cartridges, and, in fact, derived from the 30-06 + 300 Savage. So the 308 could, at most, have been judged under the aspect of copyright.
At this point, I shall not utter any ill-judged opinions with rude personal comments, as seems to be the norm for this thread, but make a lengthy quote from the Sierra Rifle Reloading Manual, on the assumption that Sierra, judging by the proved performance of their bullets, actually knows something about cartridges and internal ballistics.
"Shortly after the end of World War I, the U.S. Ordnance Corps bagan looking for a smaller cartridge to replace the.30-06 Springfield. With typical government efficiency, the quest was still underway near the end of the Second World War. By 1944, engineers at Frankford Arsenal had begun to experiment with the .300 Savage case. .... After a long series of modifications, a revised cartridge case designated as the T65E3 was adopted as the NATO standard on December 15, 1953.....
.... While the military trials were still in progress, Winchester introduced the cartridge to the sporting public as the .308 Winchester...."
1) Sierra makes no distinction between the NATO cartridge and .308 Win.
2) Neither does CIP.
3) Winchester offered the public a cartridge that was already undergoing military trials, the culmination of many years of development. Development not exclusively by Winchester or anyone else.
4) The 7.62x51 NATO was derived by a normal process of development by those "skilled in the art" - a fundamental phrase for judging novelty in the sense of patentability. Not patentable.
5) Copyright would seem to be invalidated by the prior work undertaken by the military and those acting on their behalf.
6) Please all stop talking BS.
7) Sorry, apologies to all. The bad-mannered style of this forum is infectious.
Patrick