Interesting observations...
When you shoot in a match that only 308 is allowed for what 30 yrs it's pretty simple to say 308 is the most accurate.
That’s only happened in the USA since the late 1990's when the NRA changed the rules for what a Palma rifle had to be chambered for. Prior to that, either the .30-06 or .308 Win could be used. That was the original rule (I wrote it in 1989 for the NRA) so folks shooting their M1903's, M1917's and M1's or any other rifle with .30-06 chambers could compete without having to get a new barrel or rifle. But the NRA High Power Rifle Committee wanted more folks to shoot .308's as that’s the only round allowed by International Palma Competitions.
Until the middle 1970's, the cartridge requirement for NRA match rifles was it had to be 30 caliber and for special matches allowing any caliber, they had to be no larger than 8mm.
I could see NRA going to the 308 for those matches since other countries have a say on what's being used.
Explained above, but here’s more details. The USA has only one member on the International Palma Committee. All the others feel its best to have everyone shoot the same ammo to “level the playing field.” No handloads allowed as that would give some an advantage that’s not equal acoss all competitors. As the present cartridge is the NATO standard, that’s what they want to use from local arsenals and that’s what they vote for making the rules.
When the 30-06 was dropped if it was only for accuracy why didn't the retest the classification system given using the 30-06. Same when they changed target size.
.30-06 cartridges were never dropped by the NRA as a legal cartridge except for what Palma rifles had to be chambered for (see above). The classification system had to be the same because the rules allowed any 30 caliber cartridge. And both were used in the same match, same division and same category all on the range at the same time. Target scoring ring sizes for high power matches were changed for 200 to 600 yard targets in 1966 and 800 to 1000 ones in 1972. That was done because of the high numbers of unbreakable ties shot by folks using more accurate cartridges and having to follow NRA rules to break ties. ‘Twas caused by .308's being used all the way to 1000 yards (mainly service and Palma rifles past 600) and shorter 30 caliber magnums in “any rifle” divisions for long range matches. But that didn’t prevent some folks using .30-06's and .300 H&H’s trying to outscore .308's and. 30-.338's or .300 Win Mag’s; they never succeeded overall but on rare occasions they did win.
The .30-06 was never dropped by the NRA High Power Committee for match rifles. The NRA rule for decades had been the NRA match rifle had to be 30 caliber; no specific case shooting 30 caliber bullets was stated. Someone could have used a .300 Savage, .30-.30 Win. Or even the .30 Carbine at all stages through 600 yards. Someone decided to shoot a .308 Win. in 1963 and won that year’s Nationals. Others with his skills tried both .308 and .30-06 cartridges in equal quality rifles; the .308 shot more accurate. A few years later, the 5.56 NATO round was allowed in service rifles for that division. Soon thereafter, any caliber under 8mm was allowed; including the .30-06. The .30-06 fell out of favor as it was easier to get more accuracy using the .308 Win. and smaller caliber cases as soon as good bullets were available for them.
NRA is a score shoot also classification system but it's not perfect in that once you get to High Master you never have to shoot to that level again. Maybe that's one reason they never retested.
A common belief, but not so. Once you’re assigned an NRA classification, you have to shoot at least the scores that got your that classification else you dropped to a lower one. If you don’t shoot at all for several years, you get to start over again at the bottom. New shooters typically start as “unclassified masters.
Besides winning they give classification awards
And sometimes a lower classified shooter gets an award for shooting a lower score than a higher classified one shot and didn’t get an award.
On another thought:
But the velocity of the 30-06 does have an edge over the 308 in a bolt rifle. Not much of an edge but 200 fps on average is still a edge.
If one compares muzzle velocity between these cartridges when the only difference is the chamber and cartridge dimensions, they'll see the average muzzle velocity difference is about 100 fps. Check the pages listing each cartridges' muzzle velocity and pressures for different bullet weights for their standard specifications in:
http://www.saami.org/specifications_and_information/publications/download/206.pdf
Of course, if you supercharge either cartridge, it'll shoot a given bullet out faster. But that makes the playing field no longer level. Doesn't matter that it's less accurate winning the race to the target.
It boils down to free choice; that's what people did watching the .308 Win. shoot better scores when several cartridges were allowed. Same reason the .308 Win. started disappearing in the late 1990's when 28, then 26 and finally 24 caliber bullets became as accurate as the 30 caliber ones. People shifted to those ligher recoiling ones shooting bullets that bucked the wind good enough. Folks are free today to shoot .30-06 cartridges in virtually all high power rifle matches. Nothing prohibits that.