.30-06 pressure question

[uad7116]

maybe I'm thinking about this all wrong but when I look thru my reloading manuals why is the pressure for the .30-06 always lower than all of its siblings (.25-06, .270, .280, .338-06, etc.)? I thought maybe with the smaller bullets would be higher pressure, but the .338-06 has higher pressures listed. And lastly I never load over what the book list as a max load (with or without signs of excess pressure), would the .30-06 when loaded to the pressure's of the other cartridges (assuming its safe) be a faster velocity than what the books are listing? Sorry if the way I worded this is confusing, but I know what I'm trying to ask and hopfully yall will too, thanks Kris

[Eric in NC]

The 30-06 is older and the pressure standard was lower when it was commercialized - and it has remained that way.

Also it has been loaded in a ton of rifles that may not be good choices for the higher pressures (thinking of Winchester 95's etc.).

In a strong, modern design, no reason it can't be loaded to the same pressures as the more modern cartridges.

[uad7116]

so then if it is loaded to the same pressure wouldn't that be a increase in velocity? and if so what kinda gain would I roughly be looking at?

[Eric in NC]

Every rifle and load is different - you may not be able to reach published max loads in your rifle without seeing pressure signs (have a couple of 06's like that) or you may be able to get so far over published max loads without pressure signs that it starts to scare you (have a couple like that too!).

All I can say (if you are interested in getting the MAX fps possible) is to work up carefully and check brass carefully. I have not found the 06 to be one of those that groups better and better all the way right up to the ragged edge (22-250 and 223 are examples of that in my experience). My 06's usually group best somewhat below max loads.

[Doug B.]

All I can say (if you are interested in getting the MAX fps possible) is to work up carefully and check brass carefully. I have not found the 06 to be one of those that groups better and better all the way right up to the ragged edge (22-250 and 223 are examples of that in my experience). My 06's usually group best somewhat below max loads.


More often than not, any rifle I own, irregardless of caliber will group better using reduced loads often far from published max loads.

[BillPa]

Another thing on pressures is how it was determined and listed, CUP( copper units of pressure) or PSI ( pound per square inch). The CUP was obtained using the crusher method. In the recent 10-15 years or so with the event of strain gages (piezo-electric) some cartridges have been updated to the PSI figure.

From a Shooting Times article...

We seldom saw these effects in rifle cartridges. Most standards for bottleneck cartridge chambers place crusher and transducer ports much closer, at least as a percentage of total chamber length. We shot transducer pressures for .30-06 loads with the various styles of Speer 180-grain bullets, data for which had previously been developed on crusher only.

The crusher loads were set to max between 47,000 and 48,500 CUP, just under the SAAMI max of 50,000 CUP. Transducer testing showed that the same loads fell between 56,700 and 58,500 psi, just under the 60,000 psi limit for the same cartridge. No changes in published data were needed. Across the range of modern rifle cartridges, we did not find any surprises when we added transducer data to our existing files of crusher data.

Transducer testing provides a direct payoff to the hobby reloader: volume of data. We had to budget 50 percent more time when developing loads that still used crusher standards. Transducer testing let my team greatly expand the coverage in the latest Speer manual.

So the published pressures depends on how it was determined and if it was updated to reflect the PSI figure or listed as the old CUP data. It still boils down to staying within the recommended loading data for a bullet and powder combination for a particular cartridge.

In any event without the equipment you'll only have an approximate idea on pressures. I have had times when the loading was increased with noticeable signs of the pressures increasing while the chronographed velocities decreased.

In other words, load a 308 Winchester as a 308 Winchester, don't try to turn it into a 300 Win Mag! ;D

http://www.shootingtimes.com/ammunition/ST_cuppsireloaddata_200905/index.html

Bill

[amadjuster]

SAAMI lists MAXIMUM chamber pressures as 60,000 PSI in the 30/06. I sure would not try this in a WW1 Springfield or 1917 Enfield!

http://www.lasc.us/SAAMIMaxPressure.htm

[uad7116]

I'm not looking to load it to something crazy, I never go above what the book says no matter if I have no pressure signs. Just wondering if the .30-06 is lowballed in the books, and as long as i have no pressure signs then I could slowly and carefully work up until I start seeing some signs of over pressure, and if I do that then I could possibly be over what the books states a velocity. I know all guns are different and show signs of pressure at different points and a chronograph is the only way to tell a true velocity, but right now I am loaded to the max load in the book a are 25 fps behind its speed and have no pressure signs and thought I could maybe get a little more, not looking to get .300 win mag, if I got 50 to 100fps I'd be thrilled, and I'm still happy if i get nothing, and accuracy is the biggest factor but good accuracy and a little more speed wouldn't be bad either. Thanks for your replies, Kris