Caliber 5.56 NATO vs. 7.62x39

I consider the subject of this article to be one of the three major arguments in the gun community. There’s Glock vs. 1911, 9x19 vs. .45 ACP, and 5.56 NATO vs. 7.62x39. Caliber wars can be exhausting, and the answer is so subjective, I don’t think there will ever be one that’s definitive. However, unlike picking your favorite football team, choosing a caliber is usually influenced by data and logic. The purpose, availability of ammunition, and type of weapon can and should influence your caliber selection. Today, we’re going to look at the individual properties of our contenders, then compare the two.

Fast and Light: 5.56x45mm

The 5.56 is an intermediate cartridge. The .22 caliber projectile is small and gains its effectiveness from its velocity. Depending on the specific load, 5.56 can reach velocities ranging from 1,100 to over 3,000 feet per second. The most popular bullet weights are 55-grain, 62-grain, and 77-grain. Barrel length also plays a large part in the effectiveness of the round. Longer barrels, like the original 20” barrels used in the Vietnam conflict, give the bullet a much higher velocity than the now popular 10.5” or 11.5” barrels.

The 5.56x45mm was based on the .223 Remington, which was developed hand in hand with the AR-15. It saw extensive use in Vietnam, and users began criticizing the cartridge, stating that it often failed to pitch and yaw, leaving targets on their feet. This problem worsened as barrels were shortened. Originally, 7.62x51mm was adopted by NATO, but after realizing that it was unwieldy during fully-automatic fire, 5.56 was adopted.


  •  Bullet weight: 55gr, 62gr, 77gr
  •  Bullet diameter: .224”
  •  Case length: 1.760”
  •  Velocity: 1,100 - 3,000+ FPS
  •  Maximum range: About 600 yards

In many ways, 5.56 is the 9mm equivalent in its own caliber war. The smaller cartridge means that more rounds can be held in a smaller space. The cartridges themselves are lightweight, meaning shooters can carry far more rounds on their bodies. Felt recoil is minimal when firing 5.56, and a wide range of accessories and aftermarket parts are available to tame it even further.

Photo Credit: Bronson Eguchi

One of the biggest drawbacks to the caliber is that its ballistic performance relies on pushing a small projectile at breakneck speeds. This means that the bullet has the possibility to go through a target much easier, as well as leaving a small hole.

Slow and Heavy: 7.62X39

The 7.62x39 is the most common caliber in the world. People have been using it to gain or eliminate freedom for decades. The cartridge is based around a .30 caliber projectile. Velocities can hover around 1,000 FPS on the low end, but exceed  2,400 FPS on the high. Bullet weights vary, but the most popular are in the 120-grain range. While the round is primarily known for its association with AK-pattern rifles, some have sought to cram the chunky round into AR-15s. Due to the shape of the round, curved magazines are necessary for reliable feeding.


  •  Bullet weight: 117gr, 123gr, 124gr
  •  Bullet diameter: .309”
  •  Case length: 1.524:
  •  Velocity: 1,000 - 2,400 FPS
  •  Maximum range: About 400 yards

If the 5.56 is the 9mm, 7.62x39 is the .45 ACP. The bullets are heavy, consequently making them slow. The recoil impulse can be stout, but feels more like a gentle push than a hard punch. The size of the round also means a large wound channel, giving the bullet a higher chance of damaging a vital target. Inexpensive surplus military ammunition is often easy to come by, which also makes it easier to afford long days on the range.  

Photo Credit: Ryan Ogborn

The weight of x39 ammunition is one drawback that can’t be ignored. All of that weight adds up quickly and can lead to fatigue. Also, while inexpensive ammunition can be found relatively easily, much of it is old, corrosive, and can have issues with reliability. Due to the shape of curved magazines, good mag holders can be difficult to locate.

Which is Better?

There is no right answer to this question. I know it's boring, but the truth is that, like all things, both calibers have pros and cons. I honestly don’t believe that one is better than the other. Just like the 9mm vs. .45 debate, it all comes down to the shooter’s personal preference.

Both rounds will give you the result that you want, but which one can you consistently control and connect with? Which is most readily available where you live? Are you someone who buys a box at a time, or do you have cabinets full of ammo? With which can you afford to train? All of these factors are more important when deciding on a caliber than their ballistic performance, because if you can’t fill a magazine or hit your target, what’s the point?

Now, if I had to give my personal opinion, I would select 5.56x45mm. Yes, I am an American, so 5.56 and .223 ammunition is very much available (even with current events). However, I base that decision more on the idea of making more small holes than less big ones. The controllability and low-weight ammunition mean that I can hit where I aim and have plenty of rounds on me if I don’t. 7.62x39 might hit harder, but you can carry almost twice the amount of 5.56 in the same size ammo pouch. The massive aftermarket for 5.56 is another huge draw. If you have a specific purpose for your bullet (hunting, home defense, military), someone out there makes a special loading just for you. I don’t know of many 7.62x39 loadings meant for taking deer. However, if anyone has some 7.62x39 that they want to give me, you know where to find me! Be sure to do your research before deciding which you prefer and continue to train!

Nic Lenze

Nic Lenze


Did you find this article helpful?
Share it with your friends