300 Blackout Vs 5.56 NATO: There’s Really No Comparison

The 300 Blackout Vs 5.56 conversation is like debating apples and oranges.

The Bright Line Between 300 Blackout and 5.56 NATO:

• Similarities between the cartridges end with them sharing the same case and being tailored for military use.
• Thanks to its higher velocities, the 5.56 is much more adept at longer ranges.
• The standard .22-caliber also performs better out a longer barrel.
• 300 Blackout is less finicky about barrel length and is excellent out of SBRs.
• The .30-caliber is hands down the more suppressible of the two, with ample subsonic loads available.

By now, most everybody knows the 5.56×45mm NATO cartridge. Its fortunes tied to America’s most popular rifle—the AR-15—the small-bore thunderbolt has become among the most shot centerfire cartridges in the world. As it goes, success breeds competition, and since its adoption by the U.S. military more than one contender has attempted to knock it off its throne. Most have proven mere pestering flies to the king, but not the 300 Blackout.

Admittedly, Blackout—formally known as the 300 ACC Blackout—is still very much a niche chambering compared to the 5.56 NATO. AR-smiths across the board offer the latter, not so the former. Yet, the .30-caliber cartridge’s popularity and stability are impressive, especially for an AR option dubbed by many naysayers as a “flash in the pan” from the start. By far, the .300 Blackout is the second-most popular AR chambering of all time and arguably earned consumer shooters’ respect quicker than even the old standby AR cartridge.

For those who don’t already have both in their gun locker, the 300 Blackout vs 5.56 NATO question is pertinent. There are few dividing lines quite as bright as the one drawn between the two most popular AR cartridges on the market.

History Of Service

Most times, the history of a cartridge’s development sheds light on its particular aptitudes, given they were tinkered to specific performance specifications. This is especially true when it comes to the 5.56 NATO and 300 Blackout. Both were tailored for military service, and used the Soviets’ 7.62×39mm cartridge as their measuring stick. But each was dialed in for much different operational settings, and thus excel in different areas.

5.56 NATO

The 5.56 NATO origin story runs through the turbulent 1960s and the Vietnam War. The knives had been out for the service rifle America entered the war with—the M14, chambered in .308 Winchester/7.62×51 NATO. Lackluster performance against North Vietnamese’s AK-47s sealed the rifle’s and cartridge’s fate, as politicos and the Pentagon went searching for a lighter, intermediate option that mirrored its adversary’s weapon.

Eventually, the AR-15 (M16 when adopted by the military) and 5.56 NATO became the choice. What made the 5.56 NATO so appealing for warfare were two main factors: weight and cost.

A single round of 5.56 NATO weighs substantially less than a single round of 7.62. Therefore, a soldier could carry more on his person, and the logistic corps could fit more rounds per truckload. Given numerous post-World War II studies showed proximity to the enemy and volume of fire were keys to winning a firefight, the .22-caliber was perfect for the job. Since it’s a smaller round, requiring less material to construct its bullets and a smaller powder charge to launch it, it was also less expensive—particularly compared to its .30-caliber predecessor.

While it might irk some old-timers—and not delving into the horrendous rifle failures of Vietnam—the 5.56 made for better marksmen as well. The 55-grain bullet moving at 3,250 fps (original specs from the military’s first load) from the AR-15’s muzzle showed improved hits over the M14 and 7.62. The round remained supersonic out to 500 yards and passed the Army’s penetration tests in spades, making it a deadly effective intermediate option—one serving the country wells since 1964.

300 Blackout

How do you get 7.622×39 ballistic performance out of an AR? Seems the answer is the 300 Blackout. Just don’t think the relatively new cartridge was the first crack at seating a .30-caliber bullet in a .223 Remington case. J.D. Jones did a spell before Advanced Armament Corporation got the Blackout standardized by the Sporting Arms And Ammunition Manufacturers Institute (SAAMI) in a little wildcat known as the .300 Whisper.
(Patrick Sweeney has an exceptional write-up on the 300 Blackout vs .300 Whisper and their minute differences.)

Whisper or Blackout, the cartridge is extremely innovative on several levels. Not only does it do a bang-up job of replicating the icon Soviet cartridge’s ballistics, but it does so with minimum modification to the AR platform. Barrel switch and that’s it; you've gone from 5.56 to 300 Blackout. Bolt, magazine, gas system can all stay the same.

That’s handy, but what the cartridge is best known for is what its wildcat predecessor was created for—suppression. Go heavy with bullet weight, say 220 grains, and subsonic in velocity, and the 300 Blackout is as quiet as a church mouse fart. Maybe its greatest asset is the Blackout doesn’t lose a beat shot out of short-barreled rifles, but still holds its own out of a carbine-length gun.

Bone Up On AR-15 Cartridges:

• AR-15 Calibers And Cartridges: What Should You Chamber Your Carbine?
• AR-15 Basics: .223 vs. 5.56×45 NATO
• Why Buy A 6.5 Grendel?
• .350 Legend Vs .450 Bushmaster: Does One Win Out For Hunting?

The combination of all three traits is what piqued the military’s interest, but not for any mainstream duty. Instead, special operations—hamstrung by suppressed pistol-caliber sub-machine guns and carbine—found it an especially potent upgrade. The punch of a rifle round, quiet as a PC when suppressed and adaptable to most configurations made it a flexible tool, malleable to mission criteria.

300 Blackout vs 5.56 NATO Ballistics

Given their much different ends, it’s no surprise the two cartridges contrast each other in performance. As a general rule, the 5.56 NATO shoots flatter and, true to its original parameters, doles plenty of damage out to 500 yards. Farther out, as the round stays supersonic for a spell, it takes a steady hand to keep the wind-sensitive light bullets on targets.

Theoretically, supersonic 300 Blackout has the ability to make it a threat at 500 yards, though it’s doubtful most will take it this distance. Given the mild velocities—somewhat akin to the .30-30 Winchester—and pedestrian ballistic coefficients for the caliber, its bullets drop relatively quickly. This is especially true compared to the 5.56.

An example is in order. Take the U.S. Military’s 5.56 M855A1Enhanced Performance Round (.371 BC, 2,970 fps MV ) and a somewhat comparable load for the 300 Blackout, Hornady’s 125 gr FMJ Frontier (.250 BC, 2,160 fps MV). At a mere 200 yards with a 100 zero, the 300 Blackout drops nearly 5.5 inches more than the 5.56, at 300 yards it drops a whopping 19-inches more. From there it really degrades. By and large, the relatively rapid loss of velocity confines the 300 Blackout to near medium and close ranges.

Terminally, especially in the context of hunting anything larger than a coyote, the Blackout has the upper edge. True enough, the 5.56 and its civilian counterpart the .223 Remington have taken deer and are popular (and legal) options in many corners of the county. However, numerous hunters consider a .22-caliber too light for big game, and quite a few state divisions of wildlife agree.

For instance, according to Colorado’s DOW, a big-game hunter must be armed with “Rifles using center-fire cartridges of .24 caliber or larger, having expanding bullets of at least seventy (70) grains in weight, except for elk and moose where the minimum bullet weight is eighty-five (85) grains, and with a rated impact energy one hundred (100) yards from the muzzle of at least one thousand (1000) foot-pounds as determined by the manufacturer's rating … .”

There are plenty of 300 Blackout loads that meet the criterion laid out by the Centennial State to hunt every one of its big game species. Though, dust up on your stalking skills if the smallish .30-caliber is your choice.

Rifle Configuration

For most, this is where the rubber hits the road in the 300 Blackout vs 5.56 NATO discussion. Every shape and size of AR is chambered for both cartridges, but each excels in certain configurations. Think small with the 300 Blackout and go long with the 5.56 NATO.

Since it was designed with short-barreled rifles in mind and is suitable for close-in work, the 300 Blackout makes a much more logical AR pistol option. For hunting, carbine length suffices and makes for a nimble companion in the woods.

The 5.56 more than functions in a pistol configuration, but at the sacrifice of velocity. You’ll have more than enough for CQC if that’s your aim. But if you have a yen to let the reins out on your rifle or want to pick off called coyotes, you’ll likely be happier with a carbine-length barrel or longer. Hell, if you don’t foresee pieing corners, you might even consider a classic 20-inch barreled configuration, many of which are out and out tack drivers.

One last note, suppress shooting is a no brainer … 300 Blackout. It’s where the cartridge’s roots are laid and there’s ample subsonic ammunition available.

Parting Shot

It should go without saying, when talking 300 Blackout vs 5.56 in the AR platform, there’s little reason to settle for one or the other. You always have the cost-effective option of having different uppers for each cartridge, in case you can’t make up your mind. But if you run a domestic-beer budget, define mission parameters for your AR, and the clear choice of cartridge will shine through.

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