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hunterjoe21 Super Member
Joined: Mar 30, 2007 Posts: 1486 Location: Miles City, Montana
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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Wed Jul 30, 2008 3:17 am Post subject: Re: 308 vs 30 06 |
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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.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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Pumpkinslinger Super Member
Joined: Sep 22, 2007 Posts: 5002 Location: NC foothills
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gelandangan Super Member
Joined: May 07, 2006 Posts: 6398 Location: Sydney Australia
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Posted: Thu Jul 31, 2008 4:32 pm Post subject: Re: 308 vs 30 06 |
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I agree with what pumps said..
Peak pressure dont determine the final velocity.
_________________ A straight line is the shortest distance between two points.
A smile is the shortest distance between two people.
Do - Not try!
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Dimitri Super Member
Joined: Nov 25, 2005 Posts: 5944
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Posted: Thu Jul 31, 2008 7:51 pm Post subject: Re: 308 vs 30 06 |
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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 )
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
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Thu Jul 31, 2008 10:24 pm Post subject: Re: 308 vs 30 06 |
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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.
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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Dimitri Super Member
Joined: Nov 25, 2005 Posts: 5944
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Posted: Fri Aug 01, 2008 4:26 am Post subject: Re: 308 vs 30 06 |
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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.
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.
Dimitri
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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PaulS Super Member
Joined: Feb 18, 2006 Posts: 4330 Location: South-Eastern Washington - the State
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Posted: Sat Aug 02, 2008 12:12 am Post subject: Re: 308 vs 30 06 |
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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.
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)
_________________ Paul
__________________
Speer, Lyman, Hodgdon, Sierra, and Hornady = reliable loading data
So and So's pages on the internet = NOT reliable loading data
Always check data against manuals
NEVER exceed maximum listed loads |
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Dimitri Super Member
Joined: Nov 25, 2005 Posts: 5944
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Posted: Sat Aug 02, 2008 5:04 am Post subject: Re: 308 vs 30 06 |
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PaulS wrote: |
We are saying the same thing, I believe, in different words. |
Yup seems that way.
Dimitri
_________________ A thousand hills, but no birds in flight, ten thousand paths, with no people's tracks. A lonely boat, a straw-hatted old man, fishing alone in the cold river snow. |
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