I remember this debate somewhat. I think the warning was meant for those using older mil-surp rechambered rifles from the turn of the century. I'm vague on the whole debate.

There is a velocity/pressure difference between .223 and 5.56, it is quite common for ARs with .223 chambers to shed crimped in primers while firing 5.56.

Me too.
I never thought about socks being ambidextrous....Somebody needs to explain that also.

I know that this is an ancient thread, but the .308 was modeled after the .300 Savage cartridge after WWII, not the 7.5 MAS. Virtually identical to the .300 case, except the 7.62/.308 has a longer case neck, to more firmly hold the bullet when used in full auto weapons.

I found out that the large difference in 5.56 NATO and .223 is that testing method, including the location of the transducer, is WAY different. And that the throat on the 5.56 is made to accommodate different rounds that could over pressure a .223.

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"He was kinda funny lookin'"

I know that works for most people, but what if one has two left feet?

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Formerly Model520Fan

Socks? People actually wear socks??
I am so glad this ancient thread has come back from the dead!

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Still Running Against the Wind

Zombie much.
I thought the .308 was a cu down '06?

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Some men, you just can't reach

That was exactly the rationale of the .300 Savage just after WWI. The Savage Model 99 rifle had been on the market for 20 years, but it had a fairly short action, too short to accommodate the .30-'06 cartridge. After WWI, it occurred to Savage that it might be easier to market the Model 99 if it could be chambered for a cartridge more or less equivalent in power to the .30-'06, so it would appeal to all those Doughboys returning from France where they became very familiar with .30-'06 rifles such as the Springfield '03 and the Enfield 1917. So they just shortened the .30-'06 case so that the loaded cartridge length was short enough to work through the Model 99 action and could be loaded to approximate .30-'06 ballistics, as the Savage 99 action was quite strong. It worked.

During and after WWII, the U. S. Army was looking for new rifle and machine gun designs which would be lighter and handier, and that would necessarily require a lighter and more compact cartridge, preferably one which was already in use, eliminating a lot of ammunition development cost. The .300 Savage best met that requirement. However after some testing, the Army decided that the stubby case neck of the .300 Savage did not provide adequate support to hold the bullet firmly enough for use in full auto weapons, so they simply lengthened the .300 Savage case neck a bit. And Voila! - the 7.62x51 (.308 Win) was born.

I learned something new.

Old thread, but I can relate to the TC's irritation towards the authors of various articles spreading misinformation because unfortunately Investigative Journalism is a lost art, and sensationalism generally attracts attention better than boring old factual information ever will amongst the sort of ignorant folks who act as if it is unreasonable to be irritated by the spread of misinformation.

Fortunately, times change, and in most circles I'm aware of, most folks in the know will tell you that 7.62 and .308 Winchester are indeed interchangeable, so the only folks it effects are the sort who acts like such misinformation isn't worth getting upset over.

It reminds me of the modern day attitudes towards .40 S&W now that it's no longer popular in Law Enforcement and all the articles making blanket statements about how 10mm Auto being a more powerful cartridge without getting into load data or actual facts, so you get ignorant people posting around forums about how their 10mm is more powerful, yet all they ever shoot are 10mm Lite/FBI which is downloaded to similar specs as your average 180gr .40 S&W self-defense load, thinking that they have something substantially more powerful. Don't even get me started on the nonsense about 10mm being as powerful as .41 Magnum.

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Shooting Comfort is bilateral.

A fuller explanation is to be found here. Chamber pressures | M14 Forum
The NATO and SAAMI chamber pressure test methods both use piezoelectric pressure gauges, but there the similarity ends. And the ancient copper crusher method is entirely different from both. Actually, the European CIP method is similar to the NATO method in principle. All four tests produce a chamber pressure number but not the same number for the same load. The CUP method is obsolete today and it is doubtful that it is still used anywhere. Sort of like comparing a sundial to an atomic clock if you want to know the time.

Still good information, and in four days we can wish this thread a happy 10th birthday!

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Alan
SWCA LM 2023, SWHF 220

I treat .223/5.56 and .308/7.62x51 as completely interchangeable and save those brain cells for something else. No problems in the last 50 years or so.

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It’s Fudd-Daddy to you.

The trouble usually starts when somebody sees the old NATO CUP number and compares it with the modern piezo methods.

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Release the Kraken

That's exactly how I remember this discussion, as being primarily about not shooting 308 Win in imported Spanish 1893 and Chilean 1895 Mausers being import marked as 308 Winchester. The point was made that they were re-barreled/rechambered for 7.62 NATO as potential wartime reserve/militia weapons. The differences between the two rounds was enough that it wasn't safe to fire 308 Win in those 130-year-old rifles originally designed around the 7mm Mauser.

As a handloader, here’s how I approach the subject. And, avoid trouble!
To begin with, I only shoot my own loads, unless I’m shooting up factory stuff to get the brass.

1). All loads are matched to the specific firearm in which they are to be used.
2). Military brass (ie: 7.62 or 5.56) has crimped primers and reduced capacity. (Keep the latter in mind even if converting to another caliber.). Develop loads and process brass accordingly.

PS: I don’t understand why there were so many replies mocking to OP. It’s an important topic that some people want clarified.

I don't know whether that is right, but I do it, too.

Hope some of you pay attention to me when I DO know what I'm posting about.

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Formerly Model520Fan

I can tell you exactly why. I had the temerity to suggest that some people's beloved .308 Win was not a dragon slaying monster when compared to 7.62 NATO. As somebody who previously worked in high end metrology, I have found that hard proof often gets up people's noses.

Years before I wrote the OP I read on another forum a guy who actually worked in an EPVAT rated facility in Canada and tested ammo said he had seen NATO ammo regularly equal and even surpass the .308 SAAMI spec on his test rig. A whole bunch of pitchforks and torches were handed out then, too. I tried to find that forum again when I posted the OP for this thread, but looks like it got lost in one of the corporate forum takeovers.

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Release the Kraken

I think I lucked out, the link does not work!!!

I am going to beat my favorite dead horse yet again.

Buy a Chronograph. Although Velocity is not an absolute measure of chamber pressure, it’s a pretty good indication. And in the end, velocity is all that matters.

Under the same conditions and circumstances, the MV is proportional to the peak chamber pressure, but it is not a simple linear relationship. If you have the Quickload computer program you can work it out.

Good on you for fighting for the Facts.

Also, Sweet baby Jane, this is an old thread.

Now can we discuss 9x19, 9mm NATO, 9mm +P, 9mm +P+, and 9mm Major?

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Psalm 27:2

There's probably a zombie thread out there to revive on those subjects, but this time I didn't start it.

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Release the Kraken

I actually have a pair of "performance socks" that my wife gave me, that are marked L and R. One day on a whim, I intentionally put them on the wrong feet. Laced up my shoes, stood up and took one step. Ran smack into myself.

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Ain't This Fun Though?

...on my 'Things I want' list. Maybe Libre or somebody will come out with a clone.

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"He was kinda funny lookin'"

By the time I finish typing this I will have forgotten what I read and it won't matter anyway ...

Back a few years I did a lot of shotgun shooting which equated to a LOT of reloading. I shot a K-80 in skeet with Briley and/or Kolar tubes. We shooters noticed quite a few split chambers in the 20 ga. Briley did some checking and found that a perfectly safe 20 ga load through the years had really high spikes in pressure when checked by PE testing. Lead crushers never read the very high momentary pressure spikes. They let it be known that we should switch powders in the 20 and 28 if loading Green Dot. . I used Unique or Herco in both and never split a tube. Just an illustration about the differences between crusher pressures and Piezo Electric testing

GEE, THANKS. Now I have something else to keep me awake when I should be getting my beauty sleep. (I really, really need more beauty sleep)