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Old January 29, 2014, 04:08 PM   #51
Bart B.
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David, if one checks the details of how the .308 became the favorite competition cartridge over the .30-06 from late 1963 through the next few years, here's what they'll observe. And the difference was microscopic. The first .308 chambered rifles that outscored the .30-06 ones were identical except for their chambers. They even used the same components except for the case.

The first bolt action rifles were Win 70 receivers originally made for .30-06 size cartridges but with a spacer at the back of the magazine and a longer bolt stop so the bolt throw would be about half an inch shorter. Barrels in competition were typical 26" long ones tapering from 1.2" at the breech to .900" at the muzzle. Hart made most of them and they all had the same bore and groove diameters that worked best with Sierra's bullets. Both had 1:11 twists. A few people tried using the Rem. 700 short action but it had too many faults to make any realistic comparison between short and long actions with .308 barrels in them. As it turned out, those round ones didn't hold bedding as good as the flat bottom/sides Win 70's did and, along with magazine feed, trigger and extractor problems, the 700's were not popular.

The semiauto version was the M1 with the difference between the old .30-06 parts list, a 7.62 chambered barrel made by Springfield Armory in MA with a slightly larger gas port and a 1:12 twist. It took the M14 shops an extra year or so to work out the details of making them shoot as accurate as the 7.62 Garands, but they finally did it. Both shot more accurate with aftermarket match barrels; almost as accurate as what bolt guns did.

Both the 7.62 NATO and .30-06 peak pressure specs as measured by arsenal copper units of pressure systems were identical; 50,000 cup. What Winchester used for their .308 Win cartridge was a different cup system and therefore had different numbers emerge from it. Otherwise, both cartridges operated at the same peak pressure.

Someone told me years ago that Remington went to 1:10 twists for their .308 chambered barrels because most customers thought that was the best for heavier bullets. Didn't matter that Winchester used 1:12 with great success even with 200-gr. round nose bullets. That does make it cheaper to use the same mandrel for hammer forging the same 1:10 twist 30 caliber barrels for all sorts of cartridges.
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Last edited by Bart B.; January 29, 2014 at 04:18 PM.
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Old January 29, 2014, 07:03 PM   #52
DAVID NANCARROW
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Bart, if you will pay closer attention to my post, I mentioned that a lot of the commercial rifles used a 1:12 twist in their 308 chambering. Nothing mentioned about Hart barrels or specialty target rifles. If you care to look at Big Green's current offerings in 308, you will find that more than half of them still give the 1:12 twist barrel to the 308.
I notice that Savage tends to lean toward the 10 twist, but I really don't know when this began with that firm.
Winchester seems to offer the M70 in 308 with a 1:12 twist only.

Not so sure what special CUP rating the 30-06 used to use, but SAAMI spec shows in PSI that the 06 max average pressure is 60K while the 308 is 62K. I chalk that up to some of the older rifles chambered in 06 as compared to the newer steel alloys available in the 1950s
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Old January 30, 2014, 11:13 AM   #53
Bart B.
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David, I noticed what you're reminding me of. My post was put up to explain what detailed and valid reasons were behind the .308's better accuracy than .30-06's when it's preference for accurate cartridges originated.

There's lots of info on the 'net stating the arsenal pressure systems used on military small arms ammo set both the .30-06 and 7.62 NATO round at 50,000 cup. That's still the SAAMI spec for the .30-06, but Winchester's different sytem details for CUP measurements for their .308 Win case were established at 52,000 cup as easily seen on pages 15 and 16 in:

http://www.saami.org/specifications_...wnload/206.pdf

Read post 4 in the following:

http://www.xcrforum.com/forum/19-308...62-x-51mm.html
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Old January 31, 2014, 06:04 AM   #54
DAVID NANCARROW
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Agregory, I have no personal experience with the scope your package comes with, but I do have some with the Howa in 30-06. It seems to be a pretty decent, reliable action. They also have a good reputation for accuracy. Feed it decent ammunition and do your part, and I believe you wont be disappointed!
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