AmmoLand writer Logan Metesh examines the history and development of .300 Blackout and 5.56 NATO ammunition.
AR platforms are probably the most popular platforms on the market today. The gun was primarily designed for the 5.56/.223 caliber and has been adapted to a variety of other calibers over the years, but none has gained as much acceptance as the .300 Blackout. Let’s take a look at the pros and cons of .300 Blackout and 5.56 NATO ammunition.
History of 5.56/.223
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The origins of the 5.56 and .223 calibers are the same as many other calibers that have been popular over the years, and were promoted by the military.
The era of the powerful battle rifle has come to an end. The M1 Garand and M14 rifles were phased out in favor of a new, radically different rifle, the M16.
ArmaLite’s new rifle design required a new caliber, but the original intent was not to reinvent the wheel. Initially, they floated the idea of using a commercially available .222 Remington round, a popular varmint round. Unfortunately, the caliber was not up to military specifications, so we had to go back to square one.
What emerged was a similar but distinctly different cartridge, the 5.56x45mm round developed by James Sullivan, who collaborated with Eugene Stoner on the rifle’s design. This ammunition was officially adopted in the United States in 1964, and a “civilian” version known as the .223 Remington was also soon produced.
However, NATO was not satisfied with this new ammunition. I had just recently switched to 7.62x51mm and was in no rush to change again to another new round that I deemed inferior. Eventually they relented and in 1980 the 5.56x45mm round became the NATO standard.
Both the 5.56 and .223 rounds have proven themselves in military and civilian markets alike. After nearly 60 years of use, it’s safe to say that both are here to stay.
.300 AAC Blackout History
The relatively new .300 AAC Blackout turns 10 this year, and has accomplished quite a lot in just 10 years. Work began in 2009 by designer Robert Silvers as a joint venture between Advanced Armament Corporation (AAC) and Remington Defense.
As the story goes, in 2009 a military customer approached the company about using a standard M4 (AR) bolt and magazine that could hold 30 rounds and fire .30 caliber projectiles. . Work continued until 2010 and the cartridge was approved by SAAMI in January 2011.
The result was the .300 AAC Blackout, which sat on the shoulders of the earlier Wildcat cartridge known as the .300 Whisper.
Although the .300 Blackout has military roots, no organization has officially adopted it across the board. But it’s very popular among AR enthusiasts looking for something a little different.
Advantages and disadvantages of .300 Blackout and 5.56 NATO
The biggest advantage of 5.56/.223 ammunition is its popularity. Well, at least until the 2020 ammo shortage begins. I’ve had no trouble finding this caliber, whether I wind it myself or buy it ready-made each time. Because this caliber was used everywhere and by almost everyone.
Are you out of ammo at the shooting range? no problem. The pro shop was supposed to have boxes in stock. It’s not like I ran out of something I don’t understand, like 10.15x63Rmm.
One of the biggest drawbacks is the sound suppression. Using a suppressor on a firearm of this caliber will certainly lower the decibels, but it won’t truly make it “hearing safe.” Also, just because the volume is acceptable doesn’t mean it’s safe. Oh, and if you want to run it with a 7-inch pistol build? Ha! Forget it! You’ll probably want to keep the Ear Pro on hand.
.300 AAC Blackout Advantages and Disadvantages
The biggest advantage of the .300 Blackout is that it allows for caliber versatility for the AR platform with minimal changes to the gun itself. All you need is another barrel, and given the Lego-like nature of the AR, swapping it out is as simple as removing two pins and tapping in a new upper receiver.
You can use the same bolt, the same charging handle, and the same magazine. If uniformity is important to you, you can also have an entirely new upper with the same physical setup, just a different barrel caliber. Quite witty.
However, where the .300 Blackout really shines is when used in conjunction with a suppressor. Subsonic loads are surprisingly quiet when fired from an AR with a suppressor. Even with the short barrel length, it does a great job of suppressing decibels without sacrificing overall performance.
One of the downsides to this cartridge is the cost. Similar in many ways to the 5.56/.223, but at a different price. .300 Blackout definitely costs more per round.
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But this cartridge’s biggest drawback is also one of its biggest advantages. That is, the gun shares parts with the 5.56/.223 cartridge. However, the .300 Blackout is designed to fill regular AR magazines to maximum capacity, so any careless loading or oversight could result in a magazine filled with the wrong ammunition.
However, things get worse. You can put a .300 blackout round in a 5.56/.223 barrel, but you can’t fire it from that barrel without catastrophically malfunctioning the gun and putting yourself at risk of serious bodily injury. Absolutely not.
So you have to be careful about which magazines have which bullets in them and which uppers are attached to the lower receiver.
.300 Blackout vs. 5.56 NATO Who Wins?
To be honest, I think it’s a draw. Both are great for their purposes and have their place. I think it will be up to the individual entries to choose the true winner. If all you care about is suppressing your shots, it’s hard to beat the .300 Blackout. If you’re a casual AR enthusiast, the 5.56/.223 is the way to go.
That being said, variety is the spice of life and guns don’t have to be “Sophie’s Choice”, so why own both?
About Logan Metesh
logan Metesh I am a historian who focuses on the history and development of firearms. He owns High Caliber History LLC and has over 10 years of experience working at the Smithsonian Institution, National Park Service, and NRA Museums. His ability to present history and research in an engaging manner has made him a sought-after consultant, author, and museum expert. He is very good at Jeopardy!, as he can easily recall obscure historical facts and figures, but he is exceptionally bad at geometry.
