.308 Winchester vs. 7.62x51 mm pressure

So does this mean that .223 and 5.56 are also about the same?

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Originally Posted by Gutshot John

So does this mean that .223 and 5.56 are also about the same?

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Nothing to do with .223 VS 5.56. The freebore is considerably longer in 5.56 NATO which is the major issue between the two.

Here's an article that goes into pretty good detail about the differences between the two. http://how-i-did-it.org/762vs308/

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Originally Posted by shootist~

Should have stopped him right there. It's an Internet Rumor that just won't die.

You cannot compare the military measurement, which is 52,000 PSI with the copper crusher gauge to the SAAMI 62,000 PSI which is a piezoelectric transducer gauge measurement.

Military measurements in CUPs VS SAAMI in (piezo) using other calibers such as the 30-06 show about the same spread.

In reality, Max pressure for .308 and 7.62x51 are about the same.

DIE RUMOR DIE!

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Now this makes sense and basically goes with what I had always been told. The difference is that a lot of commercially available .308 ammo are loaded towards the low-end of the pressure spectrum to mitigate the big "L". This practicereduces the possibility of causing some cheaply made commercial gun to go "boom". Not much of an issue for the military.

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Originally Posted by CarlosDJackal

Now this makes sense and basically goes with what I had always been told. The difference is that a lot of commercially available .308 ammo are loaded towards the low-end of the pressure spectrum to mitigate the big "L". This practicereduces the possibility of causing some cheaply made commercial gun to go "boom". Not much of an issue for the military.

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Speer reloading manual that I have states that .308 is rated to higher pressure [does this make it true no but I would not totally discount it neither].
http://www.thegunzone.com/30cal.html
I cant vouch for the accuracy but they state that both have been measured by transducer .308 and 7.62 and the .308 is rated to higher pressure.
My personal thought is that light magnum loads that are loaded with slower burning powder run at max press but these loads are not recommended for autoloading rifles.

The thing that makes the most sense of all is to check the headspace of any surplus rifle to make sure its not on the loose side. (And don't just use a military "field" gauge to do it.)

Even so, I've always considered the thicker Mil brass to be safer in my FALs even though I've personally set the headspace to fall between SAAMI/.308 and FN/7.62x51 minimums (or at least below a US NOGO gauge.