Is 5.56 the Best Option for Everyone?

5.56x45 NATO

Many people love the AR-15. If you are not one of them, then a large number of gun enthusiasts might tell you to go pound sand. The platform is versatile, deadly, readily available, and somewhat affordable. When shoppers first start looking at battle rifles, they tend to start at the bottom and eventually work their way up. Would be owners quickly realize that like most things in life, you get what you pay for. Entry-level ARs are often .223/5.56 semi-auto rifles with few to no options, and sometimes-shoddy construction. Guns that are more expensive offer rails with endless accessories, as well as different calibers. Just when you thought you knew everything there is to know about the AR-15, they change it up. So is a high end AR chambered in a wildcat or alternative caliber a good idea?

5.56x45 NATO
5.56×45 NATO
Shooters from all walks of life praise and denounce the 5.56/.223 for a variety of reasons. It is easy to find rumors on the internet about the lack of lethality of the 5.56 NATO round. You might be familiar with a few:

  • Ineffectiveness at long range
  • Inconsistent wounding effect
  • Poor intermediate barrier penetration
  • Ease of deflection

.300 AAC Blackout
.300 AAC Blackout, 5.56, and 7.62×39
The fact is that there are no official documents stating that the 5.56mm NATO caliber has failed in any NATO military force. On the contrary, we have official documents stating that there is no issue with the lethality of the 5.56mm caliber at all. Most NATO nations even agree that the next generation of small arms weapons by 2020 will still be using the 5.56mm NATO caliber.

So why on earth do shooters sometimes shell out big bucks to own AR platform rifles chambered in 7.62×51 NATO, .300 AAC Blackout, or the 6.8 mm Remington SPC? The answer is simple, they can! Most people I know who own an AR-10 or wildcat AR-15, already have at least one rifle chambered in .223/5/5.56 NATO. This frees them up to branch out into different areas. Having a good old .223 rifle around is good for emergencies, and as far as availability goes, the .223 is one of the most common rounds a person can find in the United States. However, some shooters prefer a bit more performance out of their battle rifles, hence the larger caliber market.

Sale ends July 28, 2019

Sale ends July 28, 2019

So which one should you buy? Well it depends on what is important to you. While no caliber is perfect for everything, some do certain jobs with a bit more reliability. The .300 AAC Blackout is my favorite. It will give you an entirely new caliber with nothing but a barrel change. The same magazines and internal components in your current 5.56 rifle will do just fine.


  • More muzzle energy than 5.56 NATO
  • Able to be suppressed more effectively than 5.56
  • Uses a larger bullet for more damage to target
  • Able to penetrate barriers more effectively
  • Supersonic and subsonic ammunition available
  • Swapping between supersonic and subsonic requires no changes to the gun
  • Can be made from 5.56 brass, easy to reload


  • Ammunition is not widely available
  • Ammunition is currently slightly expensive

The 6.8 SPC isn’t a terrible option either. It falls at about the halfway point between the 5.56 and the 7.62×51. You get a little better ballistic performance than the .300 AAC Blackout, but you have to change out your AR parts. If money were no object, the 6.8 would be an outstanding choice for a supercharged AR.

7.62x51mm NATO
7.62x51mm NATO
Then we have the good old 7.62x51mm NATO. The civilian version, the .308, is one of the most successful cartridges of all time. It’s big enough to drop big game, but small enough to deliver relatively light recoil. It is an almost ideal sniper round, and the U.S. Army’s M14 sported the cartridge. Additionally, the original AR rifle that Eugene Stoner designed was a 7.62×51. So why doesn’t everyone carry an AR chambered in .308? Cost is one factor—you have to shell out twice as much money for a .308 AR. Have you checked the price on .308 ammunition lately? Even if I were a rich man, I still wouldn’t shell out that kind of money for brass, smoke, and noise. If that wasn’t enough to keep buyers away, most .308 magazines carry 20 rounds instead of 30. Weight is another issue, since AR-10s are extremely heavy and carrying all that heavy ammo can be a real pain.

Therefore, it is ultimately going to be up to the buyer. There is no such thing as a bad AR cartridge. Most any of the oddball calibers will do fine in a combat scenario. However, due to the much lower cost and availability of the 5.56, my second AR might end up being the same cartridge as my first.

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The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (13)

  1. I am one of those old Vietnam Vets that had to actually have someone come tot he field to remove my M-14 from my hands and give me the M-16. I love the M-14 but… fickled… I also love the AR platform as well.

    I have 4 of these “NASTY” black rifles. Bought 2, built 2. 2 are in the 223/5.56 mode, one in the 308 mode and one in the 300 Blackout. Cherished place in my gun safe for all. Ammo is no issue. My son is a state cop and I get the 45acp/223/38spl( prison guards use them) brass from their qualifications twice a year. So brass is plentiful. As far as 300 Blackout… I reload all of these. I cut the 223 cases and resize for the 300…so I avoid a lot of the costs of buying 300s. So…if you have one or more of these AR platforms…maybe expand your pleasure by taking up reloading. It helps feed these “hungry” weapons. LOL

  2. I enjoy coming across articles that bring out the thoughts of 223 and 308…

    I grew up learning 22 long rifle.. that is. what my dad said. will make you good. spotting Jack Rabbits and Coyotes . 3 and 4 times a week on our Kansas ranch. The old incandescent spot light, plugged into to lighter socket in a Jeep J10; memory’s of a mission. We drove in the fresh cut wheat fields circling, looking and there it was. We stop i lean out the window, Dad would be ” Go! aim, Shoot” took me one night and missing 3 and all fell in place 3 more went down like clock work at 100 yards or better and we started a stew every week. My dad is now 85 and and I am 46. We went out with my 308 and 223 to get some stew with, Ha! led lights and nailed a few Rabbits he is still as cool a shot as ever. That is of course to his fine military training. Cheers Justin and Larry Doskocil

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