AK103K, I've shot the same .308 Win. barrel and .30-06 barrel with both 7.62/.308 ammo in one and .30-06 M2 ball/commercial-150's in the other.
The .308 Win. barrel showed a 25 fps average velocity difference between Federal Match and M852 match with Sierra 168's in each; the M852 was the fastest. Had I used two other lots of each type, the numbers may well have been reversed.
As for the .30-06 barrel, the commercial 150's were about 75 fps faster than the military M2 rounds but their bullets were a few ten-thousandths larger in diameter. Again, these number would probably reverse with different lots of ammo.
I've no idea what the pressure difference was between all this stuff, but a 25 to 50 fps spread across several barrels with a given ammo type and lot will also show that much spread.
MIL SPECs for velocity with a given ammo type's quite a bit. Their match ammo's got a +/- 30 fps average range, service ammo's a lot more. So the lot to lot difference in it will often show a 100 fps spread.
Using SAAMI's tables is probably the best way to compare the .30-06 rounds as peak pressure in both military and commercial versions are the same; 50,000 CUP. MIL SPEC test barrels have the same bore and groove dimensions as SAAMI.
