7.62x39mm and .308 Winchester: two of the most iconic and widely-used cartridges in the world, and ones that have frequently found themselves on opposite sides of conflicts across the globe. But how do these cartridges stack up against each other, especially in modern platforms? We’re going to explore the history and performance of each round, and look at the benefits that each one has to offer the civilian shooter.
A Brief History of the Cartridges
7.62x39mm
As the second World War raged on and dense urban combat became increasingly commonplace, Soviet leadership realized the need for an intermediate cartridge that could bridge the gap between the low-powered pistol cartridges used in submachine guns like the PPSh and the robust 7.62x54R cartridge used in the Mosin-Nagant rifle.
In 1943, the People’s Commissariat for Armaments met to discuss the development of a new round that could be used across a wide range of firearms, from semi-automatic and select-fire rifles to light machine guns. Soviet firearm designers came up with over 300 theoretical cartridge designs, eventually narrowing the field down to eight contenders that were actually produced and tested.
From these tests, the first 7.62x39mm precursor round was developed and approved for service. These early rounds were stubbier than the modern 7.62x39mm cartridge, and the case length was actually 41mm. As well, this bullet of this prototype cartridge lacked the tapered boat tail base, under a mistaken assumption that it would only improve accuracy at long distances after the bullet had become subsonic.
After some minor refinements, this cartridge was put into production. However, while 7.62x39mm saw some very limited front line use in prototype versions of the SKS carbine, the war ended before the cartridge could be tested in its intended role as an all-purpose infantry round.
It wasn’t until 1947 that the 7.62x39 cartridge as we know it today was finalized. After additional testing, the bullet was elongated, given a boat tail base, and switched from a pure lead core to a layered lead-and-steel core. In order to maintain the same total cartridge length, the case sleeve was shortened from 41mm to 38.7mm, rounded up to 39mm for the sake of naming convenience. That same year, the round was tested in conjunction with prototypes of the now infamous AK-47 rifle.
While minor changes have been made to the cartridge in the decades since, including bimetallic and lacquered cases, the use of heat-treated steel cores to improve penetration, and the development of armor piercing and subsonic rounds, the 7.62x39mm cartridge has changed little since 1947, and remains one of the most commonly used service rounds in the world.
.308 Winchester
Compared to the wartime origins and design-by-committee history of 7.62x39, the story of the .308 Winchester cartridge is a bit more straightforward. However, like the Soviet round, the development of .308 was also spurred by the needs of the military as typical engagement distances continued to shrink.
In fact, the U.S. Army’s search for a successor to the powerful .30-06 cartridge first began shortly after World War I, when the round proved difficult to adapt to semi-automatic rifle designs. Several alternatives were tested (.276 Pedersen being the heir apparent), but the eventual development of the M1 Garand demonstrated that .30-06 could, in fact, be used reliably in a semi-automatic rifle.
The M1 performed so well that the military saw little need to replace it during WWII, and it continued to see service during the Korean War, as well. But that’s not to say that there weren’t downsides – most notably, the M1’s limited capacity, cumbersome weight, and heavier ammunition led the Army to experiment with detachable box magazines and select-fire designs. As well, the Army began testing experimental ammunition based on the .300 Savage cartridge, theorizing that the ballistic performance of .30-06 could be more or less matched while using a shorter, smaller case that would allow soldiers to carry more ammo in the field.
These experimental cartridges, known as the T65 series, served as the basis for the 7.62x51mm round that would come to be adopted by NATO as the standard battle rifle cartridge in 1954, and those tests also led to the development of what would become the venerable M14 rifle.
But two years before NATO’s decision, Winchester saw the opportunity to introduce a version of the T65 cartridge to the civilian market as a general-purpose hunting option. Thus, .308 Winchester was born, and quickly became one of the most prolific hunting cartridges in not only the US, but the entire world.
Ballistics
A simple side-by-side glance at 7.62x39 and .308 Winchester will likely be enough to conclude that while these two cartridges shared a somewhat similar design philosophy, they perform quite differently. This is made especially clear when we look at the trajectory of both rounds over long distances using common factory loads.
While the performance of both rounds is quite similar inside of 200 yards, the gap rapidly starts to widen at about the 250 yard mark. Despite a lighter bullet, 7.62x39 sheds velocity very rapidly beyond 300 yards, while .308’s larger case capacity means it has enough propellant to keep the bullet zipping along. This is also demonstrated by the muzzle velocity – using standard 168-grain ammo, .308 Winchester boasts a muzzle velocity of 2,650 fps, compared to 2,356 fps for a 124-grain 7.62x39mm round. While .308 Winchester maintains supersonic speeds at 500 yards, 7.62x39mm typically becomes subsonic between 400-500 yards depending on the ammunition.
In other words, both cartridges will have no trouble staying on target inside of 250 yards, but if you’re consistently shooting at distances farther than that, you probably want to reach for the .308.
Ammo
When it comes to comparing ammo, there are a couple things to consider. First of all, let’s get the obvious one out of the way: price. While the golden days of extraordinarily cheap surplus 7.62x39 ammo are behind us, it can still be had for less than half the price per round of .308 Winchester. If you’re a casual shooter who just wants to maximize range time and have fun plinking, that’s all that really matters. If you’re interested in hunting or competition shooting, or just want to squeeze every last drop of performance out of your rifle, there are a few other factors worth mentioning.
While 7.62x39 is more affordable and usually pretty easy to find (barring situations like the 2005-2006 shortage or the current issues surrounding restrictions on Russian ammo imports), one of its downsides is the lack of meaningful variety. Although a few manufacturers have stepped up to offer hollow-point and soft-point bullets suitable for hunting (and even a few match grade options!), much of the 7.62x39mm on the market is still FMJ ammo, and is often corrosive military surplus.
Conversely, decades of refinement for specialized military applications, hunting, and competition shooting means that there are a plethora of options to choose from when it comes to .308 Winchester. Whether you want to bag big game, shoot suppressed, or punch paper at 500 yards, there is a manufacturer that has you covered – just don’t be surprised if your wallet feels a bit lighter afterward.
Stopping Power
“Stopping power” is often a vague term that gets tossed around without any data behind it, but there are a couple of basic criteria that we can use to compare two cartridges more objectively: kinetic energy and sectional density.
Calculating kinetic energy involves some math, but the simplest way to think of it is that it refers to the amount of energy that is transferred from the bullet to the target when it makes contact. Generally speaking, the higher the kinetic energy, the more damage to the tissue, bones, and organs the bullet passes through. For the purpose of hunting, 1,000 foot-pounds of energy is a decent benchmark for being able to ethically harvest medium-sized game like deer or pigs – below that, you stand a good chance of having to chase down a wounded animal.
So how do these two cartridges stack up?
Measuring the bullet right as it exits the muzzle, .308 Winchester packs a whopping 2,727 foot-pounds of energy on average, compared to 1,525 foot-pounds for 7.62x39mm. Right away, the difference is clear. But at 300 yards, a .308 round still packs 1,186 foot-pounds of energy, while the 7.62x39mm round drops to a mere 630 foot-pounds.
From these numbers, it’s easy to see why .308 has earned its reputation as a big game round and has seen decades of service with military and police marksmen. Likewise, 7.62x39mm’s performance makes perfect sense if you recall that it was designed to eliminate human targets inside of 300 yards.
So what about sectional density? Derived from the bullet’s weight and diameter, sectional density is a measurement of how well an object’s mass is distributed in order to overcome resistance – in ballistic terms, it lets us know how good a bullet is at penetrating targets.
The sectional density of a .308 Winchester bullet is roughly 1.5x higher than a 7.62x39mm bullet. While there are other factors involved in determining penetration potential, such as the shape of the bullet and construction of the core, these numbers tell us that .308 is most likely going to see deeper penetration when it connects, a hypothesis borne out by ballistics gel tests.
The bottom line is that 7.62x39 packs more than enough punch to put down medium-sized game within 200 yards, but in terms of raw stopping power – especially at longer distances – .308 is the undisputed champ.
Hunting
If .308 has more stopping power, that makes it the superior hunting round, right? Well, it depends on what kind of hunting you do. Plenty of deer, hogs, and coyotes are harvested with 7.62x39 every year, and the relatively low recoil makes follow-up shots much more manageable if you’re firing at a moving target. 7.62x39mm makes for a fine brush gun that’s cheap to shoot, which is certainly something worth considering if you’re looking for a gun that you can hunt with and also take out for a fun range trip without breaking the bank.
Meanwhile, .308’s reputation as an excellent hunting cartridge is well-earned. It’s a versatile round, more than capable of handling everything from deer to elk and moose – and while I’d personally prefer something a bit more powerful, many a bear has been taken with a well-placed .308 round, too.
While we’re here, a brief word on accuracy: 7.62x39mm has a bad reputation for being an inaccurate cartridge, but aside from dodgy surplus ammo with questionable quality control, that reputation is largely undeserved. In most cases, the blame really belongs to the rifle it’s being fired from – AK-47s in particular can vary spectacularly in quality depending on where they are manufactured, even after accounting for the fact that they were intentionally designed with looser tolerances in order to be easy to maintain and repair. The quality of Chinese-made AK-47s, for instance, is notoriously inconsistent, and in some countries, such as Pakistan, Iraq, and Ethiopia, design specs for manufacturing the AK-47 were all but passed down through word of mouth. Nowadays, there are plenty of high quality AKs on the market that will put rounds where you want them, so don’t let that scare you away from an excellent cartridge.
Compatibility
While the 7.62x39mm cartridge is synonymous with the AK-47 and SKS (and the Vz. 58 for our neighbors up north), it may come as a surprise to learn that it’s also becoming a popular chambering option for the AR-15.
Converting an AR is as simple as swapping out the BCG, barrel, and magazine, though you can also simply buy a complete 7.62x39 upper, letting you swap between cartridges with ease. This is a great option for shooters who want to combine the ergonomics and accuracy of the AR-15 platform with the close-range stopping power of 7.62x39mm (not to mention the access to tons of cheap ammo), or for shooters who simply don’t want to shell out the premium prices that even the most inexpensive AK clones are going for these days.
And while .308 is probably most famously associated with bolt-action rifles like the Remington 700 or Winchester Model 70, it has also experienced a modern boom thanks to the AR-10 platform, which has rapidly become a popular choice for hunters and precision shooters alike. [Shop 308 Uppers here]
As with the AR-15, the AR-10 is quite modular, and can be purchased as a complete rifle or assembled to the shooter’s specifications from a wide variety of barrel length and twist options in the form of a complete upper or a barrel swap. [See our complete comparison of AR-15s vs AR-10s!]
Best Applications
Ultimately, these two cartridges each fill a very different niche, and they have endured so long largely because they are great at what they do.
7.62x39
7.62x39 excels within 250 yards, whether it be plinking at the range or bagging mid-sized game, and relatively tame recoil makes it easy to score follow-up shots – it also makes it a nice option for introducing new shooters. If you want a cheap, reliable shooter that doesn’t need to reach out to 500+ yards or achieve sub-MOA accuracy from a benchrest, 7.62x39mm is a great choice.
.308
On the other hand, if you’re looking for a long-range cartridge with a wide variety of ammunition options and the stopping power needed to tackle most North American wild game, .308 Winchester is more than worthy of its reputation as a top-tier hunting round. It’s more expensive to shoot, and that extra power comes at the cost of significantly higher felt recoil, but that’s a small price to pay in exchange for a precise cartridge that is equally at home ringing steel plates or bagging bull moose.
[We would like to give a huge thank you to Eric Shattuck for writting this awesome complete guide to 7.62x39 vs .308! Check out our other blogs like 300 Blackout vs 308 and 223 Wylde!]
