Thread: .308 vs .30-06
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Old November 21, 2012, 05:06 PM   #63
Rainbow Demon
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Join Date: September 27, 2012
Posts: 397
The OAL limit of the .308 means that when bullets of over 175 gr are used the bullet must be seated deeply into the powder space reducing effective powder space.
For this reason the .30-06 is capable of handing the heavier bullets such as 200gr and heavier long range match bullets with much less pressure penalty at higher velocities.
The 1:10 twist rate of most .30-06 barrels is better suited to the longer heavier bullets than the 1:12-1:14 twist of .308 barrels.

While the original NATO ball load duplicated the original .30-06 ball, the 7.62/.308 is actually a refinement of the .300 Savage rather than a true all round replacement for the .30-06 as a sporting and long range target cartridge.

The Danes still use .30-06 rifles for their arctic circle patrols, the 06 being better medicine for polar bear than the .308.

PS
Standard commercial cartridge brass doesn't cold flow till pressures of 85,000 PSI or 68,000 CUP. Some cartridge brass can stand a good deal more.

PPS
Many low number Springfield blow ups were dure to defective subcontracted barrels. The barrels had been overheated during a bumping up process to from the shank end.
The burnt steel caused the chamber section to split breaking the receiver ring.
The same happened to an M-14 awhile back. Same cause, a defective aftermarket barrel.

The LN receivers were very hard but a bit brittle, even then almost all of the receivers that failed were from specific batches that had been overheated during the forging process.
One receiver that had held up the standard 75,000 CUP proof load and thousands of full power loads shattered like a jelly jar when a low pressure gallery/guard cartridge was fired. The low pressure did not expand the case well enough to grip the chamber walls, so the lugs took the full impact without delay.

PS
This spec sheet
http://www.everyspec.com/ARMY/TM-Tec...27_CHG-2_4432/
Contains several errors that are addressed in the spec sheets for procurement of propellents.
The M118 cartridge pressures are only expressed in CUP rather than PSI
M118 special ball (and the more recent M118 Long Range) has a pressure of 52,000 CUP (with max deviation of 57,000 CUP) rather than the 50,000 PSI listed in the above linked tech manual.
M80 has pressure of 48,000 CUP/50,000 PSI.

Last edited by Rainbow Demon; November 21, 2012 at 05:43 PM.
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