Black Ops: Shooting the .300 AAC Blackout

Simply having an excellent cartridge design isn't always enough for success. Timing can also play a critical role. If a design is too far ahead of the curve, it may not be embraced the way it should be. Get the timing right, though, and success can be a grand thing.

In the case of the .300 Whisper, perhaps its designer, J.D. Jones, was too far ahead of the curve. While you could argue this point, you can't dispute the success of the basically identical .300 AAC Blackout (BLK).

A whirlwind of interest has been ignited by this compact .30 caliber cartridge among AR owners. I find it interesting that many shooters who ignored cartridges specifically developed to add punch to the AR — such as the 6.5mm Grendel and 6.8x43 SPC — are embracing the .300 BLK.

While no one would say the .300 BLK is a "new" design, the concept is much older than most might realize. If you blow the dust off long-forgotten designs and search hard enough, you will eventually uncover a conceptually similar French military design: the 8x35SR. Dating back to 1917 and World War I, it was intended for use in the selective-fire Carabine Mitrailleuse 1918 Ribeyrolle (Machine Carbine 1918).

The cartridge was the .351 Winchester Self-Loading, which was then in French service, necked to accept a standard French 8mm Balle D projectile. This efficient 198-grain spitzer boattail was solid brass. The end result was a more efficient cartridge with a base diameter of .380 inch and a 35mm case length.

The gun itself fed from 25-round detachable box magazines, and with its short 17-inch barrel it was well-suited to trench clearing. It would have been a game changer were it not for the end of the war.

While few have ever heard of the 8x35SR Ribeyrolle, pretty much everyone has heard of the .221 Fireball. Introduced in 1963, this design was a shortened (35.6mm case length) .222 Remington designed for optimum performance in the XP-100 pistol. Wildcatters took note of this cartridge case and necked it up to accept .308-inch projectiles, creating the .300/.221 Fireball — an efficient design capable of driving a diverse range of bullet weights.

One person to take note of the .221 Fireball case was J.D. Jones of SSK Industries, who has over the years developed a host of cartridges — including an entire line of what he calls Whisper cartridges based on the .221 Fireball case.

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Perhaps the most famous of this line is his .300 Whisper, which he felt would be useful when used to launch heavy 200- to 250-grain bullets at subsonic velocities in conjunction with a sound suppressor. By driving a heavy bullet at subsonic velocity, the loud sonic "crack" would be eliminated, reducing the noise signature. At the same time, light 100- to 130-grain bullets could be driven at supersonic velocity.

Jones trademarked the name ".300 Whisper" decades ago and went on to offer the cartridge in a variety of platforms, including the AR-15. Trademarking the name prevented anyone else from marketing a firearm in .300 Whisper unless they signed a licensing agreement. To get around this, some companies simply referred to the cartridge by a different name — a situation that resulted in various names and different chamber dimensions for the same basic wildcat cartridge.

Although the .300 Whisper was highly regarded by a few, it did not appeal to the masses. The AR-15 was viewed differently years ago, and the lack of inexpensive factory ammunition and the assault weapons ban didn't help matters.

But when the ban expired, the AR-15 exploded in popularity, and a variety of new cartridges for this platform were introduced. In 2010, Robert Silvers, research and development director for Advanced Armament Corporation, was contacted by a government customer that wanted to know if AAC could produce firearms, with Remington Defense manufacturing .300/.221 Fireball ammunition. This request led to Silvers developing what became the .300 AAC Blackout cartridge.

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I have known Silvers for a decade, have trained with him and have long been impressed by his talent. I asked him about the development of the Blackout, and he told me the project had straightforward goals: create a reliable .30 caliber round compatible with the M-16/AR-15 platform — one that would shoot supersonic ammo that matches 7.62x39 ballistics and would be optimized for sound- and flash-suppressed fire.

Those goals, he said, led them away from calling the round .300 Fireball because they wanted a low-visibility flash signature — not to mention the fact that there were too many existing chamber drawings for wildcat versions called .300 Fireball.

The name .300 Whisper was out as well, he said, because, one, it would require licensing from Jones; and two, Silvers said the name would leave people with the wrong impression of his new round. "It implies subsonic is the primary use, and that is not the way I see the cartridge," Silvers said.

In the end, he said, they needed a fresh name so they could design the chamber exactly the way they wanted it. ".300 AAC Blackout is a name both consistent with full-power ammo but yet stealthy at the same time," he said.

"For the .300 AAC Blackout, we went back to the official Remington .221 Fireball drawing and used the exact dimensions from the rear, while doing the front portion in an optimal way," he said. "We picked a longer throat than in some Whisper chambers — to allow a 220-grain Sierra MatchKing to be loaded to full magazine length while being 0.010 inch from the rifling. That keeps pressure down and allows for full-power ammo to be loaded hotter for more velocity."

The most obvious question is why didn't they just use the Russian 7.62x39 cartridge? The 7.62x39 doesn't work well in M-16/AR-15 magazines, and it would necessitate a change in the rifle's bolt as well. Cartridges such as the 7.62x39 and others that require a larger bolt face lead to weaker locking lugs and create higher bolt thrust. The .300 BLK, on the other hand, uses the standard 5.56x45 magazine and bolt face and requires only a barrel change.

The .300 BLK's performance is a bit different than conventional rifle cartridges in that it offers two distinct levels of performance. While subsonic may not be its primary role, the Blackout does provide a subsonic option: 200- to 240-grain bullets running at speeds slower than 1,126 fps.

While they travel slowly, because these bullets have high ballistic coefficients they don't lose speed and energy as quickly downrange. The result is a round that can be an effective medium-game cartridge, one that is especially pleasant and quiet to shoot when teamed with a sound suppressor

Supersonic loads will drive 110- to 125-grain bullets at 2,350 to 2,250 fps. As the .300 BLK's case capacity is less than the fatter 7.62x39, it cannot match the Russian cartridge's muzzle velocities with equal-weight projectiles. However, for the most part the 7.62x39 is saddled with inefficient projectiles designed decades ago. Due to this, the .300 BLK can provide greater downrange performance than the 7.62x39.

The question I had was the same as many of you. How does the .300 BLK actually perform from a common 16-inch AR-15? To find out, I contacted Alexander Arms, which has just introduced complete rifles and upper receivers in this caliber. AA sent me a 16-inch carbine fitted with a stainless steel fluted barrel with a 1:8 twist and a carbine-length gas system.

It was fitted with an AAC Blackout flash suppressor, M1913 gas block and Mk10 Plus handguard. The barrel was fitted to a flattop receiver featuring M4 feed ramps and MPI bolt. The lower receiver sports a collapsible stock, making for a handy package weighing just 6.4 pounds.

For ammo I gathered together seven loads from four different manufacturers, selecting both .300 BLK and .300 Whisper loads. And here's an important point regarding these two chamberings.

"Hornady makes its .300 Whisper brass to be compatible in .300 AAC Blackout chambers," Silvers said. "However it is not guaranteed safe to use .300 AAC Blackout ammo in .300 Whisper chambers because there may be a pressure increase if they have a shorter throat.

"Think of .300 AAC Blackout as being more like 5.56mm and .300 Whisper being more like .223 Remington," he added. "A longer throat means less pressure, which means you can load ammo to be faster."

Accuracy results of the various loads are found in the accompany chart. Despite rather gusty wind conditions, the gun performed well for such a lightweight carbine. Best accuracy was obtained using Hornady's 110-grain V-Max load, but accuracy was consistent across the board. Only one load, Lehigh Defense's 140-grain, didn't perform well.

Switching from the supersonic to the subsonic loads revealed a bit of drop, which needs to be taken into account. Hornady's 208-grain A-Max load dropped 14 inches from the supersonic zero. Lehigh Defense's 200-grain load was a bit faster and dropped only 9.5 inches.

Shooting from field positions from 10 to 200 yards revealed Alexander Arms' Blackout to be a delightful carbine. Recoil is mild, allowing rapid follow-up shots, and the piece is fast handling. It carries easily, jumps to the shoulder and swings quickly. Practical accuracy is excellent. The .300 Blackout cartridge is very pleasant to shoot, especially with a sound suppressor mounted.

Currently there is a great deal of interest in the .300 BLK cartridge, which is a good thing for those interested in it because that will bring more loads, firearms, dies, components, data and accessories.

The most important thing, though, is simply to understand what this cartridge is and what it is not. It is not a magnum, and it's not something I would pick for use at distances of 500 yards and beyond. It will not out-muscle a 6.5mm Grendel or a 6.8x43 SPC. It is not intended to compete with a .308 Winchester AR-10.

On the flip side, you have an efficient cartridge that will do what the vast majority of shooters need done inside 200 to 300 yards. Teamed with a high quality bullet such as Barnes 110-grain TAC-TX Blacktip, it will slay whitetails and pigs.

Factory loads are readily available, and some are priced less than the least expensive 6.5mm Grendel and 6.8x43 SPC offerings. Brass can be made from common 5.56x45 cartridge casings by trimming them to 1.358 inches and simply running them through a sizing die. Reloading data, dies and components are readily available.

It is an ideal way to stuff a .30 caliber bullet into an AR-15. How ideal? Well, in October 2011 Staff Sgt. Daniel Horner of the U.S. Army Marksmanship Unit used a .300 AAC Blackout to win his fourth USPSA Multi-Gun national championship.

I love the AR-15 and its ability to be easily tailored to my individual tastes and desires. The .300 BLK simply increases the versatility of this wonderful platform.

Is it right for you? Only you can answer that question. But if you'd like a lightweight, quick handling and accurate .30 caliber semi-auto carbine for use inside 300 yards, I'd seriously consider it.