There DO EXIST three pressure and chamber standards for 308win/7.62x51mm.
CIP, SAAMI, and NATO EPVAT (which also shares reciprocity with CIP compliance)
CIP = Commission internationale permanente pour l'épreuve des armes à feu portatives In English, that's basically: "Permanent International Commission for the Proof of Small Arms" - This is the regulatory body worldwide, and most importantly, this is who NATO looks at for ammunition standards.
CIP Standard for 308 Winchester = 4150 bar, which is 60,190psi
CIP standard list - includes 308win in Tab 1-Rimless cartridges (might have to search for it at the top)
SAAMI = Sporting Arms and Ammunition Manufacturers Institute - This is the voluntary compliance proof registration body in the USA
SAAMI standard for 308 Winchester = 62,000psi
SAAMI standard list - includes 308win on page 43
NATO EPVAT = North Atlantic Treaty Organization Electronic Velocity and Action Time - this is the certifying standard for NATO approved ammunition. In lieu of direct EPVATbarrel testing, ammunition manufacturers CAN get NATO acceptance by complying to CIP standards
7.62 mm. STANAG 2310 and NATO Manual of Proof and Inspection AC/225 (LG/3-SG/1) D/9
NATO EPVAT standard for 7.62 NATO = 415.0 Mpa which is 60,190psi But the measurement position is ahead of the case mouth, which differs from the testing methods used by CIP & SAAMI. However, NATO EPVAT does accept approved CIP compliance as qualification.
The important things:
- Both CIP and SAAMI call the cartridge "308 Winchester" with 7.62x51mm as an interchangeable name. This is different than the 223/5.56 cartridges where US Customary vs. Metric nomenclature delineates two different cartridges within these commissions. So the name on the box actually doesn't really matter for their standards. For NATO EPVAT, 7.62x51mm, or more officially 7.62 NATO is the the official nomenclature used, no 308win anywhere. BUT - commercial ammunition labeled as 7.62x51 or 7.62 NATO are not necessarily certified as NATO EPVAT compliant unless branded as such with the NATO Circled Cross on the headstamp.
- SAAMI compliance is voluntary, nobody is required to submit their ammunition for testing. NATO EPVAT testing is only required (if CIP is not met) if you want to contract to NATO country military service, nobody is required to meet that standard for commercial/civilian ammunition. No maker in the US is required to submit to CIP. So technically, ammo on the shelf does NOT have to be 62,000psi proven, or 60,190psi proven. It could be anything the ammunition manufacturer wants it to be, higher or lower.
- Foreign made stuff, if it's compliant with anything at all, regardless of 308win or 7.62x51 on the box, will almost always be CIP compliant, not SAAMI, meaning it's loaded to lower pressure than USA manufactured ammunition COULD be loaded.
- Even though the same maximum pressure is listed for CIP & NATO EPVAT, they do not use the same position in the barrel for their respective tests, so the same maximum pressure does not necessarily represent exactly the same operating pressure curve, or even interchangeable maximum pressure.
- SAAMI, or CIP, compliant loads are not necessarily loaded to the Maximum Allowable Pressure standard, but are only assured to be beneath it. So it's very common for ammunition manufacturers to produce a CIP or NATO compliant load (which ever ends up the lowest of the 2), then have it tested and labeled as compliant for all 3. Being under the lowest qualifies for all 3. This also saves production cost for the manufacturer.
- Unless it has a NATO Circled Cross, it's a safe bet it's not been EPVAT tested, nor approved, so if it's foreign, it's likely CIP standard, if it's US, it's likely SAAMI
