Can I shoot 7.62x51mm NATO in a .308 Winchester rifle?

The common answer is yes, but it requires caution. .308 Winchester has a tighter pressure specification (62,000 psi SAAMI) compared to 7.62x51 NATO (60,190 psi). Headspace dimensions also differ slightly. Most modern .308 rifles will fire 7.62 NATO safely, but verify with your manufacturer before doing so.

Can I shoot .308 Winchester in a 7.62x51mm NATO rifle?

.308 Winchester in a 7.62x51 NATO chamber is generally considered safe. .308 is dimensionally close to 7.62 NATO and pressure levels are similar. However, .308 headspace spec is slightly tighter and some rounds may not chamber in all 7.62 NATO chambers. The M1 Garand and M14 are exceptions — use only ammunition specifically approved by the manufacturer.

What is the difference between .308 Winchester and 7.62x51mm NATO?

.308 Winchester and 7.62x51mm NATO are near-identical cartridges developed in the same era. They differ in pressure test methodology, headspace spec, and case thickness. .308 is the commercial SAAMI cartridge; 7.62x51 is the NATO military version. Cross-use is common but requires confirming your rifle's chamber rating.

Can I Shoot .308 Winchester and 7.62×51 NATO Interchangeably?

The Pressure Confusion

Different Test Methods Complicate the Comparison

SAAMI specifies a maximum average pressure of 62,000 psi for .308 Winchester, measured using a copper crusher transducer method. NATO specifies a maximum of 60,191 psi for 7.62×51 NATO, measured using a piezoelectric (EPVAT) method.

These two methods do not produce comparable numbers directly. The copper crusher method typically reads lower than the piezo method for the same actual peak pressure. When experts convert the NATO figure to a SAAMI-equivalent piezo reading, the .308 Winchester comes out as the higher-pressure round — but the actual peak pressures are broadly similar in practice.

The meaningful real-world difference is not pressure magnitude but chamber dimensions.

The Actual Risk Factor

Headspace: Where the Chambers Diverge

The 7.62×51 NATO chamber specification allows a slightly larger headspace than the .308 Winchester SAAMI spec. SAAMI maximum headspace for .308 Winchester is 1.634 inches. The NATO maximum headspace is 1.6355 inches — about 0.0015 inches deeper.

That difference is small. In a bolt gun with a tight, new chamber, firing .308 Winchester in a 7.62 NATO chamber is not a problem. Where it becomes a consideration is in worn semi-automatic chambers that are already at or near maximum headspace: the combination of the larger NATO chamber and the .308's higher pressure can cause excessive case stretching, leading to case head separation over repeated firings.

Semi-auto wear note: If you're shooting a surplus M14, FAL, or G3-pattern rifle with an unknown chamber condition, it's worth having the headspace checked with proper gauges before running a steady diet of commercial .308 Winchester.

Specification	.308 Winchester	7.62×51mm NATO
Max Pressure	62,000 psi (SAAMI)	60,191 psi (NATO EPVAT)
Max Headspace	1.634 in	1.6355 in
Case Length	2.015 in	2.015 in
Overall Length	2.800 in max	2.800 in max
Bullet Diameter	.308 in	.308 in

Hard Exception

The M1 Garand Is a Different Problem Entirely

Do not shoot commercial .308 Winchester in an M1 Garand. The M1 Garand was designed for .30-06 Springfield and specific 7.62×51 military loadings with controlled pressure curves. The gas-operated system relies on pressure timing — commercial .308 Winchester loads generate peak pressure too quickly for the M1's gas system, which can bend the op-rod. This is a well-documented failure mode, not a hypothetical.

M1 Garand rifles require ammunition loaded to specific pressure curves — either original .30-06 M2 Ball spec, or 7.62×51 military specification. There are commercial .308 loads marketed specifically as "Garand-safe" (e.g., Hornady Custom, various Garand-specific loads from Precision Cartridge). If you're shooting a Garand, use those or mil-spec 7.62×51 only.

The M14/M1A, which is derived from the Garand, uses a different gas system and handles commercial .308 Winchester without this issue.

Practical Guidance

Modern Rifles: Usually Fine

In a modern bolt-action rifle — Remington 700, Tikka T3, Bergara, Savage — chambered in either .308 Win or 7.62×51 NATO: both cartridges are interchangeable without meaningful risk. The chamber tolerances on new production rifles leave plenty of margin.

In a modern semi-automatic — AR-10 pattern, SCAR 17, SR-25, HK91/G3 pattern — with a new or good-condition chamber: generally interchangeable in practice. If the chamber is worn or surplus, verify headspace first.

Military surplus 7.62×51 ammunition varies in age, storage conditions, and loading spec. Modern commercial ammunition from established manufacturers (Federal, Winchester, Hornady) is consistent and safe. Older European or Eastern Bloc military surplus is less predictable — inspect brass condition after the first few rounds if you're using it in a marginal chamber.

Bottom Line

In modern bolt guns and purpose-built semi-autos: interchangeable with minor caveats on case life in NATO chambers. Never use commercial .308 Winchester in an M1 Garand. Verify headspace on any surplus semi-auto before sustained use.