To Mr. Guffey's point: yes! The 7.62 NATO cases made in the U.S. and in some foreign countries tended to be heavier than commercial .308 Win cases, but the spread was mostly about ten or twelve grains or so, averaging around 175 grains, and the difference in internal capacity was not enough to matter to most non-match shooters, much less to cause dangerous pressure when the same load was used in them all.
Then in 1988, Middleton Tompkins talked Sierra into designing the 155 grain Palma Match bullet and Winchester into designing cases for the Palma Match ammunition that had to be provided by the U.S. Palma organization for the 1992 Palma match, which was to be hosted in the U.S. Under the rules in effect at that time, the host country had to provide not only the ammunition to be issued at the match, but identical practice practice ammunition that had to be shipped to the participating countries around the world before the match.
Tompkins wanted maximum performance, so the bullet was the maximum weight allowed under the Palma rules in effect at the time to minimize wind deflection, and he wanted enough velocity so it remained reliably supersonic all the way to the 1000 yard Palma targets. The cases were to be made to maximize powder capacity. Winchester addressed that by coming up with their semi-balloon head design with a small trough around the primer pocket and making the head as low in height as they could get away with and the walls minimally thick.
The resulting case design weighed only 150 grains, which was 25 grains lighter than average cases and 30 grains lighter than average Lake City cases. It had 2.5 grains more powder capacity than an average case, and suddenly the big spread in .308 Case weight and capacity was on. Winchester must have liked their head design because it found it's way into their commercial cases and into other calibers over time. But as time passed, the weight started creeping up.
I bought some Winchester bulk .308 Cases about fifteen years ago that averaged 156 grains in weight. Recent reports have them back up over 160 grains and closing in on Remington's weight, which I last had in bulk at about 168 grains. Not all that weight difference is in actual capacity, as mentioned previously, but Metal God's recent measurements of case capacity have them all a good bit closer together in actual practice than they were when the Winchester Palma case was first out. I think the effects of the Palma design on brass spread have run their course, and now that International Palma rules have changed to allow 5.56 and handloads (IIRC) and still better bullets and powders are available than there were almost 30 years ago, it isn't as hard to stay supersonic to 1000 yards and there doesn't seem to be a lot of reason for the capacious cases anymore.
, I'm loving the shell holder on the Co-Ax, never having used one but clicking on unclenick's YouTube link, how does the shell holder work? The operator is effortlessly slipping cartridge cases in and out with seemingly no trick whatsoever.