Confused

[stevencraig]

I am confused on 308 Win vs 30-06 Sprng. Can someone tell me how 48gr of 4064 in a .308, and 52gr of 4064 in 30-06 using same bullet, show close to identical velocities? At least in the Nosler Reloading Data?

 

[chav0_12]

I am confused on 308 Win vs 30-06 Sprng. Can someone tell me how 48gr of 4064 in a .308, and 52gr of 4064 in 30-06 using same bullet, show close to identical velocities? At least in the Nosler Reloading Data?

The 308 is a more efficient case design. Shorter, kinda fatter but not really, sharper angles makes a cartridge more efficient. Hence the development of the WSMs and SAUMs. The whole reason the military moved to the 308 was because it could "duplicate" what the 30-06 was doing in a shorter cartridge and action. While the 30-06 has more case capacity and more energetic powders now can produce better results. This wasn't necessarily the case when the 30-06 was abandoned in favor of the 308.

 

[stevencraig]

Thanks for clearing that up, it was just hard to wrap my head around.

 

[OG10]

The rest of the story is….with 48 grains in the 308 and 150 grain bullet read like 107% Casefill with 52 grains and 150 grain bullet and a 30-06 your at 91% case capacity so yes the numbers appear very similar however the amount of powder in the actual case is definitely different In relation to the case fill volume

 

[1mechanic]

Yes like OG10 said but add 10% more powder to the 30-06 and then see want you have.

 

[bultinkle]

The difference is the 308 is running at higher pressure

Just like every other smaller case that claims "efficiency" as why their velocity is as high.

 

[marksman1941]

Also you might look at the most efficient powders for each case. It's not imr4064. It's a fantastic old standby, but not the best velocity by any means. Look at the best velocities at full case fill in each caliber and you'll see a marked difference.