308 Winchester vs 7.62×51 NATO: Are They The Same?

When most gun owners consider 308 Winchester vs 7.62x51mm NATO, not much thought goes into it. We’ve become inundated with the idea that the two designations are interchangeable, and in some ways, they are. However, there are differences, and we’re doing to check those out and tell you how that affects your trigger time and ammo choices.

308 Winchester vs 7.62×51 NATO Spec Comparison

Why Compare 308 Winchester vs 7.62×51 NATO?

Considering how common it is for 308 Win and 7.62x51mm NATO to be dismissed offhand as the exact same cartridges, it makes sense to pause and take a closer look. Comparing the two cartridges side by side gives shooters the opportunity to find out what the actual differences are and to decide whether those nuances affect them.

If you have a rifle chambered in 308 Win, you’ve probably already been running 7.62x51mm NATO marked boxes of ammo through it from time to time. Or maybe you have an older rifle with a 7.62x51mm NATO chamber designation, and you’re not sure how to proceed. Regardless, being a well-educated gun owner makes you a safer shooter, and we’re here to give you the details you can use to further your shooting skills through the power of knowledge.

It’s the cartridge vs. cartridge face-off: 308 Win vs. 7.62x51mm NATO.

7.62×51 NATO Review

There are fewer resources and loads available for 7.62x51mm analysis, but they do exist. This information is found heavily on the military side, but there are also commercially available 7.62x51mm NATO loads on the market. Let’s see how they measure up.

7.62×51 NATO History and Purpose

The 7.62x51mm NATO has a rather interesting backstory thanks to the way it was developing by the United States military via the Frankford Arsenal. It was actually in the 1940s when the Frankford Arsenal got to work on their line of T-65 experimental cartridges, and the 7.62x51mm NATO that eventually resulted wouldn’t see duty use until 1954. So, what was the T-65 and how did it evolve into the cartridge that’s the cousin of 308 Win?

There were six cartridges in the T-65 experimental cartridge line. They were somewhat based on the 30-06 Springfield and 300 Savage, the latter of which is typically considered the real parent cartridge of the 308 Win. In its earliest iterations, the T-65 cartridges took a few steps before matching the metrics of the 7.62x51mm NATO. It was the T-65E3 that finally met the 51mm and 20 degree shoulder measurement, and that was the fourth of the six experimental cartridges designed. 

Some of the details of the 7.62x51mm NATO development and timeline are murky, but we do know the United States military officially adopted the cartridge for duty use in 1954. The military eventually achieved their goal of creating something new for military use with the T-65E5, which was designated 7.62x51mm NATO. This cartridge is still being used by the military today, although there are frequent talks about replacing it with something else.

Pros and Cons of 7.62×51 vs. 308 Win

Best Ammo for 7.62×51 NATO

The number of commercial loads for 7.62x51mm is somewhat limited and largely consists of target rounds. Our top picks for specific uses of the 7.62x51mm NATO:

308 Win Review

Yes, 308 Win is similar to the 7.62x51mm NATO. Technically, the two don’t share parent cartridges, and they do have some differences. Read on to learn more about how the two vary.

308 Winchester History and Purpose

The 308 Win beat 7.62x51mm to market by a couple years. Military tests and trials for their T-65 experimental cartridge took some time, and somewhere along the way Winchester set eyes on it. Although it’s not entirely clear how that happened, Winchester ran with it because they felt the cartridge could be a big hit for civilian use. They did tweak it first, so while the 308 Win and 7.62x51mm NATO might appear to be an exact match at first, the reality is they aren’t precisely twins.

Pros and Cons of 308 Win vs 7.62×51 NATO

Best Ammo for the 308 Winchester

There are lot of good ammo options for the 308 Win. That is one of it’s many positives. Here are a few ammo deals we found for you.

Differences Between 308 Win and 7.62 NATO

Differences between the two cartridges include:

• 308 Win has a higher maximum pressure than 7.62x51mm NATO
• 308 Win has slightly greater case capacity than 7.62x51mm NATO
• 308 Win case walls are typically slightly thicker than those of the 7.62x51mm NATO
• 308 Win headspace is usually a fraction of an inch shorter than that of the 7.62x51mm NATO

As you can see, the 308 Win isn’t precisely the same as 7.62x51mm. Winchester designed it for commercial use and it gained traction fast among hunters, and part of that extra nudge is thanks to higher pressure. Although a couple thousand psi might not seem like a significant difference, it can be those minor changes that matter.

308 Win has been on the market for more than seven decades and still manages to maintain a devoted following. You can find guns chambered in 308 Win in all types of platforms from AR-10s to bolt-actions to AR-pistols and then some. It’s an impressively versatile round and the ballistic results are great as well.

Ballistics Comparison: 308 Win vs. 7.62×51 NATO

Although 308 Win and 7.62x51mm NATO seem like the same thing on the surface, there are a few differences. But do those nuances translate to changes from a ballistic perspective? Unfortunately, information about 7.62x51mm NATO ballistics tends to be somewhat limited and generalized, but we’ve pulled together what we can.

To compare cartridges beyond 100 yards, we’re going to take a look at a few different loads. First, let’s consider Winchester Match 7.62x51mm NATO 175 grain HPBT with a ballistic coefficient of 0.496 against Federal Premium Power-Shok 308 Win 180 grain JSP with a ballistic coefficient of 0.382.

Distance (yards)	Winchester Match 7.62x51mm NATO 175 grain HPBT. Velocity (fps)	Federal Premium Power-Shok 308 Win 180 grain JSP (fps)	Winchester Match 7.62x51mm NATO 175 grain HPBT. Energy (ft-lbs)	Federal Premium Power-Shok 308 Win 180 grain JSP (ft-lbs)
0	2600	2570	2627	2640
100	2511	2345	2284	2197
200	2424	2131	1977	1816
300	2094	1929	1704	1486
400	1938	1740	1460	1209
500	1791	1565	1246	979

Interestingly, the 7.62x51mm NATO load in the chart above manages to produce more velocity and energy than the 308 Win. Although the two loads have close bullet weights, their ballistic coefficients differ, and so do the loads in general. This is a great lesson in the fact that two rounds with the same or similar bullet weights can still produce differing results on target. That’s why it’s so important to zero your rifle and practice with the specific ammunition you intend to use.

If we change over to target loads and compare Winchester USA Valor 7.62x51mm NATO 149 grain M80 FMJ with a ballistic coefficient of 0.456 and Federal American Eagle 308 Win 150 grain FMJ with a ballistic coefficient of 0.408? Does it stay the same, or are the results a little closer?

Distance (yards)	Winchester USA Valor 7.62x51mm NATO 149 grain M80 FMJ Velocity (fps)	Federal American Eagle 308 Win 150 grain FMJ Velocity (fps)	Winchester USA Valor 7.62x51mm NATO 149 grain M80 FMJ Energy (ft-lbs)	Federal American Eagle 308 Win 150 grain FMJ Energy (ft-lbs)
0	2790	2820	2575	2648
100	2591	2597	2221	2246
200	2401	2385	1907	1894
300	2219	2183	1629	1586
400	2045	1990	1383	1319
500	1878	1808	1167	1089

From the standpoint of comparing velocity and energy, these two loads seem to be a lot more closely matched. To delve a bit deeper, let’s consider the trajectory of the two loads.

Distance (yards)	Winchester USA Valor 7.62x51mm NATO 149 grain M80 FMJ Drop (inches)	Federal American Eagle 308 Win 150 grain FMJ Drop (inches)	Winchester USA Valor 7.62x51mm NATO 149 grain M80 FMJ Wind Drift (inches)	Federal American Eagle 308 Win 150 grain FMJ Wind Drift (inches)
0	-1.5	-1.5	0	0
100	0	0	0.8	0.8
200	-3.6	-3.6	2.9	3.3
300	-13.4	-13.5	6.9	7.8
400	-30.2	-30.6	12.8	14.4
500	-55.1	-56.3	20.6	23.3

At first, the trajectory of the 7.62x51mm NATO and 308 Win loads seems identical. Then, as the bullets travel a bit further, the 308 Win experiences just a little more drop and drift. The changes aren’t significant, but they are noteworthy simply because they exist.

7.62x51mm NATO and 308 Win do tend to deliver similar ballistics with the exact details depending on the load. Based on these charts, it would seem 7.62x51mm NATO is just a little better than the 308 Win. But how does that translate on target?

When it comes to the proof on paper, 308 Win is usually more precise than 7.62x51mm NATO. This is likely because the 308 Win loads vary quite a bit more and there are greater options available. With the more limited pool of 7.62x51mm NATO ammo out there, it comes as no surprise it’s more of a struggle to find top-tier loads. That doesn’t mean 7.62x51mm NATO can’t match or outdo some 308 Win loads, only that it’s not generally reality.

Our Take 308 Win and 7.62×51 NATO

Let’s assume you’re running a gun with a 308 Win chamber. In that case, 308 Win ammo is going to offer everything from more options to greater precision. If you find some 7.62x51mm NATO rounds at an affordable price and you’d like to save some cash on plinking, it’s generally fine to run them through your 308 Win chamber. But when you really want to fine tune things or participate in a more focused sport, you’re going to need 308 Win.

If the rifle in question has a 7.62x51mm NATO chamber, which is less common but far from impossible, it’s usually smart to stick to that ammo. The minor differences between 7.62x51mm NATO and 308 Win we addressed above may not seem huge, but in an original 7.62x51mm NATO chamber, that 308 Win can rupture. Or, on a less problematic scale, it just might not feed reliably. To make matters more confusing, there is no absolute rule on this matter, only the fact that not all 7.62x51mm NATO chambers do well with 308 Win.

Thanks to the availability of hunting loads for 308 Win, there are practically endless options. On the 7.62x51mm NATO side, there’s not much out there. Most of that ammo is for target shooting, with the occasional match load making an appearance (Winchester seems to have most of these). And while you might be comfortable using match loads for defensive purposes in your 7.62x51mm NATO, if your gun is actually a 308 Win chamber, just use that ammo. Your options are far greater. 

We did not discuss barrel length in this article, but here is a good article on rifleshooter.com discussing how barrel length impacts the 308 Win/7.62 NATO.