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Originally posted by wistrapper:
I've read articles in different periodicals and reloading manuals that suggest the .222 and .308 Win as being "Inherently Accurate". What is it about them that make them inherently more accurate than another cartridge of the same caliber?

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No BS about it.Case design is crucial to a cartridges "inherent accuracy".Just take a look at the bench rest record books and see how the 6m PPC kicks butt.It has set more records than any other cartridge in history.It's little brother the 22PPC uses the same case and dominates it's class.Many of the newer cartridges are based on their design-short/fat.

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July 11, 2009, 11:46 PM #15
Bart B.
Senior Member

A friend of mine was the first person to shoot the .308 Win. in high power competition at the 1963 Nationals when it was first allowed. He won the Nationals by a handy margin and repeated it a few more times the next several years. The most accurate .30-06 bolt action match rifles at the time would hold about 5 to 6 inches at 600 yards. .308's would shoot about half that. The accuracy .308's had over the .30-06 caused so many unbreakable ties for the next three years, the NRA had to reduce the scoring ring sizes on targets to separate the outstanding scores from the excellent ones.

Meanwhile, the USN Small Arms Match Conditioning Unit got a batch of 7.62 NATO chambered 1:12 twist Garand barrels from the government's Springfield Armory then put them in a series of match conditioned M1's. Accuracy was about half of what the best 30-06 Garands produced. These Garands (also used by the USAF) shot more accurate than the other services M14NM rifles; it took the other services a few years to catch up. By the 1970's, both M1 and M14NM match versions would shoot inside 4 inches at 600 yards from accuracy cradles. The best 30 caliber Garands any of the services could build held about 8 inches at 600 yards.

Lake City Arsenal, after developing match ammo for this new round immediately noted M118 7.62 NATO stuff shot better than M72 30 caliber match ammo. Sierra Bullets used to use the .300 Savage case to test their 30 caliber bullets until the .308 Win. came out; they switched.

.308 Win. ammo from match rifles made with Win. 70 actions have shot smaller groups testing rifles and ammo at 600 yards smaller than most bench rest records at that range; .75 to 1.5 inch 10-shot groups for example. No .30-06 bullets from any barrel has even come close. Given a choice between either cartridge when both were allowed in US Palma rifles for 800 to 1000 yard matches, the best shots always chose the .308 as it was the most accurate and had less vertical shot stringing.

And though Winchester got the first contract to make thousands of 7.62 NATO ammo and commercialized the round as the .308 Win., they didn't develop it. Remington's Mike Walker (benchrest champ, designer of the .222 Rem.) headed the team of folks modifying the .300 Savage case to withstand full auto cycling. I believe they were working with Frankfort Arsenal in this cartridge development.

Bullets as heavy as 250 grains have been shot from .308's winning 1000 yard matches doing so. Not too shabby for exiting the 1:8 twist barrel at only 2150 fps.

Most of the accuracy difference between these cartridges was caused by the leade angle in the chamber's throat; 2.5 degrees for the .30-06 but only 1.5 degrees for the .308. The .308's shorter powder charge helped as well as more shoulder area and sharper angle reduced shoulder set back when the firing pin slammed the case forward in the chamber resulting in more uniform primer detonation. A .30-06 with a 1.5 degree leade angle and ammo with uniform muzzle velocity may shoot as accurate nowadays as a .308. But the milder recoil during barrel time a .308 has makes it easier to shoot accurately.

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What is it about them that make them inherently more accurate than another cartridge of the same caliber?