PERHAPS YOU NEED MORE INFORMATIVE INFO. IF YOU WERE TO USE .308 WINCHESTER DATA IN .307 WIN. OR .358 WIN DATA IN THE .356 WIN CALIBER YOU MIGHT BE IN FOR A NASTY SURPRISE

Based on this rule, find your situation below.
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I DON'T RELOAD AND USE ONLY MILSURP AMMUNITION.

You shouldn't have any problems.

I DON'T RELOAD BUT WANT TO USE COMMERCIAL AMMUNITION.

There is a potential problem with brass integrity. Commercial cases are NOT as thick as their military cousins. There is less brass, so if you use them in an original, unmeasured military chamber, there may not be sufficient material to stretch and fill the chamber without rupturing. That's bad!!

I RELOAD.

You know that commercial brass is thinner. An easy way to see this is to weigh a fired case of each type. You'll see that the commercial case is lighter. There may not be enough brass left - after lengthening - for any decent case life. You will only aggravate the situation by full length resizing (it weakens the case by overworking the brass), loading at or near maximum or both.
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If you own a milsurp bolt gun like an Ishapore 2A or 2A1, consider neck sizing the brass for better case life, fit and accuracy.

SOME FINAL THOUGHTS

Military ammunition is loaded to maximum average pressure 50,000 CUP (approximately 58,000 PSI using the modern piezo transducer method of measurement). This standard is used to ensure better consistency round to round. It is proofed at 67,000PSI. The ammunition can then be used in a wide variety of firearms with no ill effects.

Look for the NATO design mark.



NATO mark found on the outside of ammunition containers and the bottom of each case rim.


Commercial ammunition has a SAAMI/ANSI maximum pressure of 62,000PSI. While not every manufacturer may load it to this level, this is the industry established maximum. This is also measured using the piezo transducer method. The proof cartridge pressure is 83,000 to 89,000 PSI. Note the differences between the military test and operational standard vs the commercial one.

The worst case scenario for shooters of 7.62 NATO rifles is as follows: Using a commercially made, maximum pressure cartridge with long headspace, fired from a weak action (ex. converted 93/95 Mausers).

The weaker action is a possible final piece of the 308 vs 7.62 NATO puzzle.

Perhaps no single element will cause your rifle to fail. Maybe you've used your rifle for a while with no ill effects. Usually a rifle will take some abuse before failing. Like a lot of things in life, Murphy's Law - If something can go wrong, it will - could very well catch up with you.

Personally, I don't like the odds.