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I was talking to a friend today and he found some information on the errornet that stated that the commercial .308 Win ammo is loaded to higher pressures than military 7.62 x 51 mm (NATO) ammo.
I was always under the impression that this was the reverse as proven by the generally thicker base of the military cases. Can anyone point me to a difinitive reference on this (one way or another)? TIA.
I had heard this too before, but I can't remember where. With a quick search, I found the following website. I don't know that it could be termed 'definitive' or not, but until someone tells me this site is often erroneous I will continue to find it useful.
http://www.6mmbr.com/308win.html
7.62 NATO is lower pressure than .308 Winchester.
The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi
http://www.6mmbr.com/308win.html
See it has already been posted by PlatoCATM
That's interesting because I remember another website that states the opposite max pressure. I'll have to keep digging.
.308 is higher pressure than 7.62N. I dont have the link to back it up but ive looked it up before.
SAAMI and MIL pressures are measured in different places IIRC so thats why you may see some literature list 7.62N as higher pressure.
7.62 NATO and 308 Win have about the same maximun chamber pressure. You cannot directly compare the way CIP measures pressure to SAAMI to NATO, so the often cited differences are apples to oranges. I have written to many ammunition companies and even makers of pressure testing equipment to confirm this.
You do have to be careful about the pressure curve, the 7.62 N normally uses relatively fast powders and the gas port pressure so the gas port pressure is kept at bay. Some 308 can be loaded with slow powders (specially the "light magnum" kind of loads), and thus the port pressure can be vastly different with functional/durability problems in some guns.
They could be confusing the 308/7.62 with 5.56 and 223. 308 is higher than 7.62 and 5.56 is higher than 223.
My understanding has always been that 7.62 was lower pressure than .308. Generally speaking, he thicker case on 7.62 means less powder.
This is somewhat counterintuitive since 5.56 is generally a higher pressure than .223.
This should not be construed as saying that .308 is "better" than 7.62. Especially if you reload the .308 brass might be considered to be more likely to rupture or do other bad things.
I think TiroFijo is pretty spot on.
Should have stopped him right there. It's an Internet Rumor that just won't die.Quote:
Originally Posted by CarlosDJackal
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!