When selecting a semi-automatic rifle cartridge, the 5.56x45mm NATO vs. the 7.62x39mm debate remains front and center. They remain two of the most popular rifle cartridges stateside and around the globe, and for a good reason. Their terminal ballistics and effectiveness in close-quarters battle (CQB) remain second to none.

Because of this, nearly every country's military uses one of these two rounds for their primary battle rifle. But which is better suited for you?

Today, we'll take a closer look at the caliber debate that's defined world conflict since the Cold War.

What Started the Caliber Debate?

Following years of increased strain, the US and the USSR engaged in an era of détente diplomacy from 1969-1979, notable for increased trade, negotiations, and the signing of nuclear arms treaties. Détente, which means "relaxation" in French, was termed to manage relations with a potentially hostile country while preserving peace and maintaining vital interests.

While the Cold War's period of détente did not directly jeopardize relations between the US and the USSR, it was not without localized conflicts. The most notable of these conflicts was the Vietnam War, which marked the Cold War's agenda against the spread of communism without a "direct" confrontation between the two superpowers.

Within the jungles of Vietnam, the 5.56x45mm NATO and the 7.62x39mm first squared off toe-to-toe. Proponents of the 7.62x39 purported superior barrier penetration, stopping power, and kinetic energy. Fighters armed with 5.56 determined a lighter-weight bullet offered a flatter trajectory, less recoil, and better accuracy over longer distances.

The 5.56 vs. 7.62x39mm debate kicked off shortly afterward and continues today.

Which Rifle Round is Best?

Many shooters agree that the 5.56x45mm NATO and 7.62×39mm are each effective in accomplishing specific tasks. Unfortunately, due to many cartridge misconceptions and biases, the 5.56 vs. 7.62x39 debate can be difficult to navigate.

Truthfully, both rifle rounds are highly effective in CQB and long-range engagements. The 5.56x45mm NATO and the 7.62x39mm proved themselves countless times in Vietnam, Iraq, Afghanistan, and numerous other conflicts.

The 5.56 has a distinguished history of use in the hands of military and police snipers, designated marksmen, and competition shooters. Comparatively, the 7.62×39 has gotten a bad reputation for accuracy over the years—likely due to poor-quality surplus ammo.

While an SKS or AK is capable of surprising accuracy when using quality ammunition, the 7.62x39 still falls short compared to the 5.56. However, the 7.62x39 has almost twice as much frontal surface area (cross-sectional area) than the 5.56, resulting in more tissue damage and blood loss.

Regardless of which semi-automatic rifle cartridge you choose, the 5.56 and the 7.62x39 deliver in self-defense situations. But where do the cartridges stand overall?

The answer warrants a broader comparison between the 5.56 and the 7.62x39.

5.56 vs. 7.62x39mm: Cartridge Specs

Regarding cartridge specs, the 5.56 and 7.62x39 couldn't be any more different from each other. However, comparing cartridge specs is still good practice when evaluating rifle rounds.

Appearance-wise, the 5.56 has a thinner, longer case, while the 7.62x39 is shorter and broader. The 7.62x39's wider base diameter allows for more case capacity than the 5.56, which is required to push heavier caliber bullets at a velocity effective for longer ranges.

Russian nomenclature is where some of those previously mentioned misconceptions come into play. Many confuse the 7.62x39 with the 7.62x51, which fires a 0.308" diameter bullet like the 308 Winchester.

In reality, the 7.62x39 fires a 0.312", like the 303 British cartridges, whereas the 5.56 fires a 0.224" diameter. These specs allow us to recognize that the 7.62x39 fires a heavier-weight bullet at a lower muzzle velocity. The 5.56, on the other hand, fires a lighter-weight bullet at a higher muzzle velocity.

5.56 vs. 7.62x39mm: Trajectory

The term "trajectory" quantifies a round's flight path to its target by measuring inches of bullet drop. A flatter trajectory is preferred because it offers a longer effective range with less sight adjustment.

Muzzle velocity (as mentioned above) affects trajectory. A bullet moving at a higher velocity arrives at its target quicker, which gives gravity less time to deter flight path. Regarding both trajectory and muzzle velocity, the 5.56 NATO leaves the 7.62x39 in the dust.

FN Herstal designed the 5.56 to be effective at long-range and short-range engagements. The US military's lightweight, high-velocity 55 and 62-grain bullets are highly effective at this. Regarding trajectory, the 5.56 NATO cartridge is undoubtedly the flatter shooting round.

The 7.62x39 can be effective at range but requires considerable sight adjustment to compensate for the massive bullet drop experienced outside 300 yards. In 400-yard tests, the 7.62x39's 123-grain bullet plummets over 44", while the 5.56 NATO's 62-grain bullet drops about 23".

Ballistic Coefficient (BC)

Ballistic coefficient (BC) represents how well a bullet stands up to wind and air resistance. Essentially, it's a numerical measurement of how aerodynamic a round is. The higher the BC number, the better it is.

Bullet weight and design play equal roles in BC calculation, so you can't assume that a higher bullet weight will result in a higher BC. With this said, the 5.56 actually has a higher BC of 0.29, while the 7.62x39 sits at 0.27. It's not a huge difference, but it makes the 5.56 more wind resistant than the 7.62.

Sectional Density (SD)

Sectional density (SD) measures how well a bullet penetrates a target. We calculate it by dividing a bullet's mass by its cross-sectional area. The greater the SD number, the more effective it is at penetrating a target.

Most people assume that the heavier the bullet, the greater the sectional density. While valid for many rounds, it's not true for all. For instance, while the 7.62x39 offers a heavier bullet weight, it travels at a slower foot per second (FPS) than the 5.56. The two are virtually identical, with a 0.181 SD for the 5.56 and a 0.182 SD for the 7.62.

5.56 vs. 7.62x39mm: Recoil

Considering that the 5.56 and 7.62x39 are primarily frontline ammunition for combat troops, having a round with less recoil is preferred. Less recoil allows for faster follow-up shots during semi-automatic fire.

Felt recoil considers bullet weight, rifle weight, and case capacity. A lighter bullet with a lower powder charge has less recoil than a heavier bullet with a more significant powder charge.

Semi-Auto Fire

The 5.56 NATO cartridge typically fires a 55 or 62-grain bullet, while the 7.62x39 tends to fire 123-grain. Assuming an average battle rifle weighs around 7 lbs, the 5.56 NATO will have approximately 5 lb-ft of felt recoil compared to the 7.62's 8.5 lb-ft in semi-auto fire.

Despite the difference, the 7.62's felt recoil is not oppressive. Those who utilize the AR-15 state it has virtually zero recoil, as the buffer tube and recoil buffer within the AR platform soften the exchange of the bolt carrier group (BCG) during firing.

Full-Auto Fire

In the case of full-auto fire, there is a significant difference between the two rounds. Without a mount or bipod (think M249 SAW OR RPK), the heavier recoil of the 7.62 is more challenging to control due to muzzle rise.

Consider the 7.62 in the Ak-47, for example. The rifle's short-stroke gas piston, lack of recoil buffer, and heavier recoiling rounds lead to more muzzle rise during automatic firing. It requires additional strength, training, and practice, to control. The M4 carbine, with its 5.56 NATO cartridge, is easier to handle in full-auto.

5.56 vs. 7.62x39mm: Accuracy

Compared to the 5.56, there's no denying that the 7.62x30 has gotten a bad rap for being an inaccurate round. The AK platform and inconsistencies in ammunition have contributed to this belief.

Reliability is one of the most critical factors for a battle rifle, and the AK platform holds up to undying reliability. Mikhail Kalashnikov designed the AK with looser tolerances to achieve this reliability. Unfortunately, these looser tolerances, especially in the chamber, often led to decreased accuracy.

Any differences between rounds will affect the point of impact, especially when firing multiple rounds. Former Communist Bloc manufacturing processes were known for their inconsistencies in powder charge and bullet seating depth of 7.62x39 ammunition.

Additionally, surplus 7.62 cartridges tended to be steel cased, which did not form a tight seal around the chamber during firing. Poor malleability led to the deposit of carbon fouling and gasses in the chamber, which added excess wear and tear to the rifle's internal components.

Most newly produced 7.62x39 ammunition is considerably more consistent than its surplus predecessor. However, understand that even the most expensive 7.62x39 will not compare to the consistency of 5.56.

Which Round is Best for Hunting?

While initially designed for battle, both rifle rounds have found a place within the hunting community. However, the 5.56 NATO and 7.62x39 suit radically different tasks and prey.

The 5.56 (and 223 Remington) flat trajectory and lightly constructed bullets make it great for taking shots at small, thin-skinned animals like groundhogs, prairie dogs, coyotes, foxes, and bobcats. With its light recoil, follow-up shots are a breeze. But remember—as a varmint and small-game round, the 5.56 cartridge isn't legal for deer hunting in most states.

The 7.62x39, on the other hand, can step in as a hunting round appropriate for deer, feral hogs, black bears, and other medium-sized game. However, we recommend it for use at 150 yards or less. The 7.62x39 is available in hollow and soft point ammo, providing appropriate terminal ballistics to claim the game humanely.

Which Round is Best for Home Defense?

Regarding self-defense, there's no denying that both rifle rounds will get the job done. They have proven themselves on the battlefield for well over sixty years. However, it's unlikely that you would be packing a semi-automatic rifle out in public instead of an easily concealable pistol.

Therefore, home defense becomes a more pertinent topic for the 5.56 vs. 7.62 debate. One of the most important things to consider for home defense is overpenetration. The last thing you'd want is for the round to pass through the attacker and into an innocent bystander.

The 7.62x39 gained a sizable reputation in Vietnam due to its ability to penetrate barriers and brush to meet its target. However, it's not suited for home defense for this very reason. A 7.62x39 would have no issues blasting through a modern dwelling into your neighbor's unit.

While the 5.56 offers less kinetic energy, it cavitates, tumbles, and fragments when entering soft tissue. This development causes additional damage to the target while limiting overpenetration.

Which Round is More Affordable?

The price of ammunition is essential to consider when comparing different rifle cartridges. Compared to larger cartridges like the 308 Winchester, the 5.56 and 7.62x39 have remained affordable. However, with 5.56 production currently outpacing the 7.62x39, it's cheaper and easier to equip your AR-15 than your AK-47.

At around 40 cents per round, steel-cased 5.56 and 7.62x39 cost roughly the same, but it's different when comparing brass-cased ammo costs. Most shooters today pay anywhere from 38-60 cents/round for standard brass 5.56. Brass 7.62x39 is less common and costs 50-70 cents/round.

Another thing to consider is availability. While availability used to be equal between the two, pandemic-related supply chain issues, import bans, and sanctions against Russia have caused the 7.62x39 to decline in availability. While still available online and on most shelves, the number of brands has drastically reduced.

What About Reloading?

Reloading allows shooters to tailor their cartridges to meet specific needs and customize the "perfect" round. It also tends to be cheaper than buying factory-new ammunition.

223 Rem brass and 0.224" diameter bullets are inexpensive and easy to come by, lowering your cost per round. For those new to reloading, keep in mind that there is no exclusive 5.56 NATO die on the market. Since the case dimensions for 223 Remington and 5.56 NATO are the same, a 5.56 specific reloading die is unnecessary.

Unfortunately, reloading is not an option for the 7.62x39. The 7.62 brass cases and 0.312" diameter bullets are hard to come by. It remains cheaper to shoot bulk steel-cased 7.62x39 ammunition than reload it.

Which Caliber Do I Choose?

Our history is full of the 5.56x45 NATO and the 7.62x39, and it's crucial to remain open to the potential benefits of other cartridges. Too often, a shooter may neglect one due to loyalty to the platform they shoot. Yet, both cartridges are effective and offer advantages when used in the right situation.

The 7.62x39mm is a hard-hitting cartridge designed to quickly put a lot of lead into a target. Its punishing kinetic energy and terminal ballistics will make short work of any attacker. However, the 7.62 suffers from a poor trajectory past 150 yards, which limits the round's effective range.

The 5.56x45mm NATO keeps riflemen in mind with its design. The flat shooting cartridge remains effective at short and long-range with low felt recoil. However, 5.56 lacks extensive barrier penetration and is somewhat prone to deflection when encountering something en route to its target.

Which round you choose is entirely up to you and your shooting style. No matter which cartridge you choose, ensure you are proficient with your rifle in its intended use. And, as always, make sure you check out Ammo Planet's bulk stock of ammunition, daily deals, and accessories.