5.56 vs 7.62x39mm: Ballistics Match of Tortoise and the Hare

Every shooter has seen or heard of 7.62x39mm and 5.56 NATO…when you are building an AR, cruising a gun show, or staring at a wall of ammunition at your local gun shop.

These two cartridges are some of the most abundant ammunition choices on the planet. For good reason as well, considering that most major, and minor military forces on Earth use one of these two cartridges.

But, which is better, and does it matter?

5.56 vs 7.62x39
5.56 vs 7.62×39

Table of Contents

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A Brief History Forged in Warfare

The 7.62×39 Ruski was established towards the end of WWII by the Russian government in 1944. It was designed to be an intermediate range cartridge and gained a lot of traction once the Russian government designed the AK-47 and put it into military use.

You can read more about the history of the AK, 7.62×39, and learn more in our AK-47 Buyer’s Guide and our Best AK-47 Ammo articles!

Once China adopted the round, among other countries in Africa and South America, 7.62×39 chambered weapons and the ammunition proliferated.

China Military training with 7.62
Chinese Military training with 7.62×39

As far as ammunition choices for the 7.62x39mm go, its pretty plain and has not changed much in its history.

Most commercial loads use a bullet weight of just over 120 grains, and the bulk of the ammunition is either full metal jackets, hollow points, or pointed soft points.

Due to the fact that the 7.62x39mm actually uses a .310″ projectile and brass casings aren’t as plentiful, this probably isn’t the round for the reloaders among us. The Truth About Brass Vs. Steel Case Ammo.

The 5.56 NATO was originally designed off of the commercial .223 Remington load, and it was adopted by NATO countries in 1961. The concept of the 5.56 NATO was that is was smaller than the previous 7.62 NATO cartridge, which meant troops in the field could carry more of it.

Considering that the majority of shots taken during warfare are missed, having extra ammo on hand was and is still a good idea.

Marines from various units within Okinawa prepare for their turn to fire the table two portion of the annual rifle range qualification, Jan. 12, 2017, at Camp Hansen, Okinawa, Japan. The Marine Corps revised table two of the marksmanship program October 2016 to increase marksmanship skill and realism in a combat environment. The Corps requires Marines to annually qualify at the range to determine their marksmanship skill. (U.S. Marine Corps photo by Lance Cpl. Andy Martinez)
Marines at Camp Hansen, Okinawa, Japan prepare to shoot their rifle qualifications (U.S. Marine Corps photo by Lance Cpl. Andy Martinez)

During the 5.56 NATO’s history, projectile weight has changed a good bit, much like my wife when she randomly changes outfits before we go out.

Since the .224″ caliber projectile is popular with the .223 Remington, reloaders can really fine-tune a cartridge for maximum accuracy at the range or in the field.

For those that don’t reload, there is a cornucopia of choices between 5.56 NATO and .223 Remington factory cartridges. We have a list, well a complete guide actually, to our favorite 5.56/.223 ammo.

But Does Size Matter?

Foregoing the innuendos, and “that’s what she said” jokes, does the concept of smaller calibers hold water for lethality? In my opinion, and in the opinion of militaries across the globe, it does, given one important element. VELOCITY.

Author engaging targets out to 400 yards with ease with the Lead Star Arms Barrage chambered in .223 Wylde with Federal 5.56 NATO M193 ball ammo
Author engaging targets out to 400 yards with ease using a Lead Star Arms Barrage chambered in .223 Wylde with Federal 5.56 NATO M193 ball ammo

To do a quick physics lesson, kinetic energy equals half of the mass multiplied by velocity squared or K.E. = 1/2 mv^2. Velocity tends to be an important factor when calculating kinetic energy on a target considering it goes up exponentially.

Mass is obviously important, but the faster it goes, the more potential damage it can do. Also with velocity comes further effective ranges.

Hangover Math Gif

When you look into the ballistics of a common 123-grain FMJ the muzzle velocity is around the 2,350 fps mark.

It’s a reasonable velocity for a short-range cartridge, but because of its mediocre ballistic coefficient, at 300 yards, there is 26″ of drop with a 100-yard zero and hits with 550 ft. lbs. of energy.

Albert Einstein probably said this... probably.
Albert Einstein probably said this… probably.

Now when we look at a 5.56 NATO with a 55-grain M193 cartridge, muzzle velocity is around 3,000 fps, and at 300 yards, there are only 10 inches of drop with a 100-yard zero.

Kinetic energy is roughly the same at around 520 ft. lbs. of energy. But when we jump up the bullet weight to a Mk262 70 grain OTM load, muzzle velocity is roughly 2700 fps, and there is only 12″ of drop when zeroed at 100 yards.

Kinetic energy then jumps up to a whopping 700 ft. lbs. I’d say the 5.56 NATO is taking the lead!

How Hard Does It Hit… Your Wallet?

The price of ammunition is definitely something to consider when comparing different cartridges. While .223 Remington steel cased ammo is roughly the same as steel case 7.62x39mm, brass cased 5.56 NATO has a large difference in price.

A simple search on LuckyGunner shows that 7.62x39mm steel case ammo only costs .21/round while 5.56 NATO costs upwards of .37/round. (Although to be fair – you can find .223 for around .28/round)

Author zeroing a PSAK-47 Liberty Classic
Author zeroing a PSAK-47 Liberty Classic

While many people don’t mind shooting steel cased .223 Remington, some ARs will just not properly cycle it, and it can cause premature wear in barrels. Availability is about the same between the two cartridges, but in good conscience, I have to give the 7.62x39mm the nod on price per round.

Spicy Memes
Bullet Bae

This benefit may be a deciding factor for many people on a budget that want to shoot as much as possible. Whether you just want to punch paper, train with your rifle, or go out and dispatch some hogs or deer hunt, the 7.62x39mm definitely wins this round.

More ammo means more fun, and I don’t think anyone can refute that.

Variety Is the Spice of Life

When you dive into the depths of choices for rifles, it starts to get a bit dicey. Rifle choices are plenty, and ultimately, they are dependent on the shooters preference. Between AR15s, AK variants, the Ruger Mini-14, Mini-30, or the SKS, there are plenty of semi-automatic rifles that you can choose from.

Author handling the Palmetto State Armory AK chambered in 5.56 NATO.
Author handling the Palmetto State Armory AK chambered in 5.56 NATO.

Some are even interchangeable now that more and more people are interested in AR15s chambered in 7.62x39mm, and on the other side of the coin, the AKM variant chambered in 5.56 NATO by Palmetto State Armory.

So in the end, does it really matter?

The choice is ultimately up to you and what you want in your rifle. Either way, the next time you are on the range, put casings on the ground and have fun!

If you are interested in the AR-15, you’ll want to drive into our AR-15 Complete Buyer’s Guide.

What would you rather have – an AR-15 in 7.62×39 or an AK in 5.56 NATO? Let us know in the comments! Check out more info in our Ammo & Reloading section too.

28 Leave a Reply

  • Phil

    I've owned both, the AR15 in X39 is the way to go. You can run a super short barrel and still have good performance. FYI I sold the "AK chambered in 556" (saiga 223).

    4 months ago
  • Kent

    I’d like to have both. I have an AR15. Saving up for an AK47. Good read. Thanks.

    8 months ago
  • bert

    My question is bullet is kinetic energy vs. imparted energy. In looking at ballistics gel it would appear the 7.62 imparts more energy into the target (unkown if 5.56 bullet was full metal jacket, soft or hollow point whereas 7.62 was Power Shok). Has anybody looked at this factor? I've been told that some of the fast bullets have more impact at longer distances when they have slowed down, i.e. they are transfering energy into target vs. through target. I've been shooting 139 grain 7mm at 500 yards and it seems quite effective.

    8 months ago
    • Ken Whitmore

      Bert, it would be safe to say that the 7.62x39mm puts more energy on target due to a bigger bullet and more surface area, if you were to compare FMJs that do not expand. For home defense though, I would not recommend a FMJ. A pointed soft point on the other hand would do well in either caliber and dump much more kinetic energy on target.

      8 months ago
  • V John

    I have AR's in 5.56, 223 Wylde and one in 7.62x39. I have no favorite. They are all fun and each one has been set up for different purpose.16's 20's and a24. . I am building a long range 6.5 Grendel w/24inch barrel for long range target. I think this is a excellent cartridge . I think the 6.5 would make a perfect military cartridge.

    8 months ago
    • Ken Whitmore

      It definitely would make an excellent cartridge for the military. The problem though is logistics. I dont see the military ever switching from the 5.56 NATO anytime soon. Big reason would be the lethality of newer 5.56 offerings. The MK262 ammo is the bee's knees and offers excellent terminal ballistics against soft targets.

      8 months ago
      • Erik Libucha

        I actually read somewhere (not sure its true) that the military uses FMJ because although a kill is great,the real object is to wound. The idea being if a soldier or 2 is helping get a wounded man to saftey that would be 3 less people possibly putting shots on target for the time being no matter the length of time. Anybody know if any truth to this?

        6 months ago
        • Tax

          The Hague Convention of 1899, Declaration III, prohibited the use in international warfare of bullets that easily expand or flatten in the body. It is a common misapprehension that hollow-point ammunition is prohibited by the Geneva Conventions, however the prohibition significantly predates those conventions

          2 weeks ago
        • David, PPT Editor

          I have never seen a true source for this statement, I have seen it repeated though. I do not believe it is true in any form, there are a long list of reasons why fmj may be used and only a few for HP ammo. For many nations the use of expanding rifle ammo is a war crime, this is probably the largest reason why it is rarely used.

          6 months ago
  • Eugene

    For one of your future articles can you please do a guide on how to build an AR in a 7.62x39 caliber (I guess sometimes referred to as AR-47). Your guides have been invaluable to me. I have build a rifle and a pistol using your guides and with parts you recommend. I've also bought other gear based on your reviews and guides. Have been wanting a guide for an 7.62 AR! 7.63x39 AR is not trivial and a little more involved than just putting an upper together. There are different Mag (P-products vs ACS), different barrels, different BCG. To put one together requires a bit more tinkering, maybe using different weight buffer, maybe an adjustable gas block, The biggest challenge I've seen people disucss is which barrel to get so that the M4 feed ramp can properly feed the large 7.62x39 round. Some people suggest taking a Dremel to a barrel extension. Hope you can shine some light and recommend a barrel. Faxon is often recommended, but their 7.62 is a bit pricey. How about a $99 KAK industries value line, or maybe Spitna Precision (and numerous others, CBC, ArStoner, KAK, green mountaine, etc...) Would love to read one of your guides! Also, maybe you can compare some pre-built 7.62x39 uppers like the ArStoner from Midway or ones from CBC industries.

    8 months ago
    • Ken Whitmore

      I actually built one for a friend. He ended up getting a Bear Creek Arsenal barrel in 7.62x39 and it had the oversized feed ramps on the barrel extension. He also got a Toolcraft BCG with a titanium firing pin to get a little more speed striking the firing pin. It can help for steel case ammo with a harder primer. He was running ASC mags, and he has been very happy with it. Runs like a champ doing fun range sessions.

      8 months ago
      • Eugene

        Haven't looked at bear Creek barrels. Thank you for the suggestion

        8 months ago
  • Heyboy

    I like reloading 7.62x39, very accurate at 100 yards (1 ragged hole) in a handy rifle. Good gun for the kids. Buddy’s grandson killed his 1st deer with it. Hit it at 50 yards, went another 50 and dropped dead.

    8 months ago
    • Mumal

      Anything is accurate at 100yds

      8 months ago
  • Salad Tosser

    Closer range, dense vegetation...advantage 7.62 Weight, accuracy, range...advantage 5.56 6.5 creedmoor for those of us who operate and are serious about it.

    8 months ago
  • For Reals?

    What?! No comparison to .50BMG?!! And here I thought this was an article about practical shooting applications! How am I going to make a choice to deal with my squirrel problem now?!

    8 months ago
    • You don’t know shiiiiit

      It’s not .50bmg but .50 Beowulf for the AR platform. Noob.

      8 months ago
    • David L

      .50 BMG for squirrels? Are you mad? .338 Lapua Magnum is clearly the only right choice ;)

      8 months ago
  • Hey

    7.62x39 for me. Ive seen numerous tests where it will go through cinder blocks or car doors and still smash a watermelon to 300 yds. 5.56 won't. Very few enemies will stand out in the open....

    8 months ago
    • Haitian Specops

      The right ammo in 5.56 will go through a standard vehicle’s door and will be able to neutralize the threat sitting inside assuming you hit where it matters. If you plan on shooting through a vehicle or walls and then blow a melon hiding behind it, get something meaner than either caliber.

      8 months ago
    • robert

      Hate to tell you my friend by no 7.62x39 round its going to 300 yrds after hitting a concert block or after going through a car... its no wonder round... Still don't want to get hit by it

      8 months ago
  • Daniel

    Of those listed only M193 will punch through lvl III body armor.

    8 months ago
    • Matt

      If you're expecting to have to shoot through body armor or obstacles you'd be better of with something in 308 / 7.62x51 (like an ar10). M193 will only penetrate at fairly close range.

      1 month ago
    • Ken Whitmore

      The reason for that is velocity. Velocity is the enemy of armored steel.

      8 months ago
  • robert

    The main reason I choose and AR in 5.56 is accuracy and less recoil. It really depends on what you want it for. If you're shooting paper from a bench, it really doesn't matter I guess... But if we are talking combat, I will take the accuracy, less recoil, less weight and more ammo that the AR platform in 5.56 gives me. There is a big difference between shooting at paper from a bench and shooting at a moving target, that is shooting back at you while you are also moving... That's when low recoil and accuracy can decide who survives the gun fight. 2 combat tours with Aco 3/505 PIR 82nd ABN as an infantryman gives me a rather unique perspective... But you certainly don't want to get hit by either of them. to each their own as they are both great weapon systems... good write up by the way.

    8 months ago
  • Mark

    I just finished building an AR in 7.62x39 after shooting one earlier this year and love it. Also, I have an AR in 556 and building one for 223 Wylde chamber. I love both calibers and each have their own uses. Thanks for the info and keep up the good work Ken.

    8 months ago
  • Richard

    This article is totally confusing. I thought you were going to compare the 5.56 to the 7.62x39 for KE, cost etc but it looks like you ended up comparing the .223 to the 5.56?????

    8 months ago
    • Scott

      Take another read I think he covered the basic advantages disadvantages of both. 233 in steel casing may have thrown you of track.

      8 months ago
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