308 vs 30 06

hunterjoe21 · Posted: Mon Jul 28, 2008 7:24 pm Post subject: Re: 308 vs 30 06

1895ss wrote:

A17Shooter wrote:

Camels are an endangered species in California. We had Army camels in the 1800's but the only ones left are in the zoos. The California griz is extinct also. Don't think we have a need fer any cartridge larger than a 17 AH.

I've been AWOL here for awhile but, didn't we do this topic last spring??

Very Happy

Bushmaster wrote:

Summer re-runs...

Well excuse me fellows .................... !! I didn't realize that this had been discussed, cause I haven't been here that much for quit some time. I also didn't know one needed permission to post here!!! No need to wonder why some people have left and why some don't come around more often!

Who pizzed in his cereal?

PaulS · Posted: Wed Jul 30, 2008 3:17 am Post subject: Re: 308 vs 30 06

hunterjoe21 wrote:

Since we know that velocity is a function of pressure, the round with the higher pressure (all other variables being equal) will produce more velocity, regardless of the amount of powder being burned.

That premise will get you into trouble. If that was true then you could get the same velocity from any powder that produced the same pressure.
The highest pressure/time interval or impulse is what proves to produce the highest velocities. The 3006 can use slower burning powders because it has more room in the case. That allows it to have a longer impulse than the 308 - especially with heavier bullets.

Pumpkinslinger · Posted: Thu Jul 31, 2008 3:51 am Post subject: Re: 308 vs 30 06

I think we've covered that pressure thing before too. The peak pressure doesn't determine the velocity, what matters is the area under the pressure curve. The red curve has a higher peak but the blue curve would produce more velocity, all else being equal.

gelandangan · Posted: Thu Jul 31, 2008 4:32 pm Post subject: Re: 308 vs 30 06

I agree with what pumps said..
Peak pressure dont determine the final velocity.

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

hunterjoe21 wrote:

To suggest that the engineers at Speer would download the .30-06 JUST to give the .308 an advantage is ludicrous at best. If you had bothered to check, you would KNOW that, as per SAAMI specs, the .308 does in fact enjoy a 2000 psi maximum over the .30-06 (62,000 vs 60,000).

Tomato Tomato (Doesn't work as well online as in person Laughing

)

SAAMI specs are at the end of the day meaningless. BOTH will safely fire in the same gun at the same max pressure whether SAAMI says so or not.

A M700 action whether chambered in a 308Win or 30-06Spring will NOT know the difference as the action is rated for "X" amount of force and thanks to both using the same case head both will translate its pressure (PSI) on the same 0.1756 sq inches of area of the case head giving you the total amount of force on the action. In the case of 60,000 PSI its only 10,536 pounds at max pressure or about 5 tons for both a 308Win, a 30-06Spring or any other with the same case head diameter and pressure.

Dimitri

PaulS · Posted: Thu Jul 31, 2008 10:24 pm Post subject: Re: 308 vs 30 06

Dimitri,
The bulk of that force is contained by the brass being held against the chamber by the pressure. But I agree that a modern rifle chambered for either round would easily handle the same chamber pressures. It's just nice that the 3006 doesn't need the higher chamber pressure to do the same job as the 308.

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

PaulS wrote:

The bulk of that force is contained by the brass being held against the chamber by the pressure.

That is true but I have no way to calculate it so its much simple to assume the case will expand and give equal pressure all around. Smile

Still you can have a action that can withstand a 120,000 PSI loading but long before that point the brass case starts to "fail" instead. Such as when a over load locks up the rifles bolt its caused by the brass not being able to shrink back to size. Which is the max pressure the brass can handle but the gun by only locking the bolt is still in its own safe zone for pressure. Smile

Dimitri

PaulS · Posted: Sat Aug 02, 2008 12:12 am Post subject: Re: 308 vs 30 06

Dimitri wrote:

Still you can have a action that can withstand a 120,000 PSI loading but long before that point the brass case starts to "fail" instead. Such as when a over load locks up the rifles bolt its caused by the brass not being able to shrink back to size. Which is the max pressure the brass can handle but the gun by only locking the bolt is still in its own safe zone for pressure. Smile

Dimitri

That action may have an ultimate burst strength of 120000 PSI but in order for the brass to expand to the point where it will not return to is former shape the chamber has to expand with it. When the chamber shrinks back down the brass doesn't and that locks up the bolt. Just one too many times doing that and fractures begin to occur in the metal of the chamber. If you continue to load even slightly over pressure you are using a hand grenade to launch bullets.
In metalurgy the working pressure of 4130 is typically 1/2 to 1/3 that of the yield strength - for a good reason.
We are saying the same thing, I believe, in different words. Reloading is best done in an atmosphere of erring on the side of safety.

"there are old reloaders and bold reloaders but there are darn few old, bold reloaders." (adapted from some famous quote somewhere)

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

PaulS wrote:

We are saying the same thing, I believe, in different words.

Yup seems that way.

Dimitri