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Max Pressure for .30-06 vs. 6.5-06/270/338-06

 
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  #1  
Old 07-21-2010, 12:14 PM
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Max Pressure for .30-06 vs. 6.5-06/270/338-06

Hi all.

First, some background:
The rifle in question is a Win M70 Supergrade in .30-06, one of the recent SC-built rifles. It has a 24" barrel. I've been experimenting with the 167 Lapua Scenar, the 175 and 190 SMK, and the 208 A-MAX. So far, I've tried H4350 and RL-22 but also have some IMR4350 to try at some point. A max COL of 3.395" allows it to feed 100% reliably from the mag. Combined with this rifle's fairly short throat, this mag length lets me seat all four of these bullets to within .010" of kissing the lands except the 208 for which I can get to within about .025". I'm using Lapua brass (now all once-fired) and Magtech primers. I recently picked up a chronograph (Shooting Chrony F1) but have yet to use it.

Now, the topic at hand:
In searching the various relaoding manuals and web forums for long range loads to develop in this rifle, I've noticed some folks use 65,000 psi as the max pressure for their handloads rather than the SAAMI max of 60,000 psi. This seems to be based on the fact that three direct descentents of the .30-06 (6.5-06, .270 Win, and .338-06) all use the same case head and web dimensions as their older relative but have a SAAMI max of 65,000 psi.

Since case strength (keeping the primer pockets tight) is the limiting factor in determining max chamber pressure for modern bolt action rifles, this appears to be a reasonable practice. Without a doubt, it will result in decreased case life and perhaps silghtly shorter barrel life (probably a nit) but it certainly doesn't seem dangerous.

What are your thoughts and/or experiences on this?

Edited to add:
I do have QuickLoad and consider it a guide but not a replacement for actual data.

Last edited by chuckhammer; 07-21-2010 at 10:06 PM.
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Old 07-21-2010, 12:26 PM
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Re: Max Pressure for .30-06 vs. 6.5-06/270/338-06

Great post. I too am interested in the responses this provokes. There are no doubt folks here who can answer this question appropriately.
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Old 07-21-2010, 03:26 PM
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Re: Max Pressure for .30-06 vs. 6.5-06/270/338-06

I don't think most folks have the training or equipment to to measure operating pressure during firing. Maybe just a fraction of individuals , other than the labs that generate loading manuals.

Are you equipped to measure pressure or just trying to decide which manual's data to use?
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Old 07-21-2010, 04:03 PM
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Re: Max Pressure for .30-06 vs. 6.5-06/270/338-06

Quote:
Originally Posted by loaders_loft View Post
I don't think most folks have the training or equipment to to measure operating pressure during firing. Maybe just a fraction of individuals , other than the labs that generate loading manuals.

Are you equipped to measure pressure or just trying to decide which manual's data to use?

All load manuals use the 60k psi SAAMI limit for .30-06 in spite of what I explained in my original post regarding the 65k psi SAAMI limit for it's "offspring" cartidges that use the same brass. This includes the 6.5-06, .270, and .338-06.

I'd like to hear from those who have experience loading .30-06 in excess of the book loads (60k psi SAAMI limit) based on this fact.
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Old 07-21-2010, 09:54 PM
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Re: Max Pressure for .30-06 vs. 6.5-06/270/338-06

If you are running the 06 above max pressure I would have someone run quickload with your powder/bullet combo to determine the powder charge and velocity at 65kpsi.

I look for the classic pressure signs as I work up charges and also use velocity to estimate pressure. I do not go above the max charges per quickload and if the velocities match those estimated by quickloads max load I do not load any higher.

In a modern bolt action a 30-06 at 65KPSI is just as safe as a 270 Win at 65 KPSI IMHO.
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Old 07-21-2010, 10:09 PM
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Re: Max Pressure for .30-06 vs. 6.5-06/270/338-06

Quote:
Originally Posted by 3006savage View Post
If you are running the 06 above max pressure I would have someone run quickload with your powder/bullet combo to determine the powder charge and velocity at 65kpsi.

I look for the classic pressure signs as I work up charges and also use velocity to estimate pressure. I do not go above the max charges per quickload and if the velocities match those estimated by quickloads max load I do not load any higher.

In a modern bolt action a 30-06 at 65KPSI is just as safe as a 270 Win at 65 KPSI IMHO.
I forgot to mention in my original post that I do have QL and am using it to approach a theoretical 65k psi. It's a bit disconcerting not having any published data to point the way, though.

I've used MontanaMarine's 208 A-MAX data as a guide as well. He's run as far as 63 grains of RL-22 using moly and a 3.46" COL.
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