The 300 Blackout cartridge has a history going back to the 300 Whisper round, developed by JD Jones of SSK Industries between the late 1980s and the early 1990s. SSK formed the cartridge case from 221 Fireball brass and expanded the neck size to load a .30 caliber projectile. Jones designed this cartridge with two loads in mind: a lighter bullet being used for supersonic rounds comparable to the energy and ballistics of the Russian 7.62 x 39 or 30-30 Winchester round as well as a subsonic load involving heavier projectiles for use in conjunction with a silencer.
SSK trademarked the cartridge and kept it proprietary; limiting other manufacturers in what they could produce such as reloading dies, reloading components, barrels or firearms. The 1994 Federal Assault Weapon Ban had a major impact on this cartridge and its use in semiautomatic rifles because there were limitations on threaded barrels and muzzle devices to one degree or another.
Fortunately, this misguided piece of legislation came to an end when the sunset clause of the law took effect in January 2004. Around that time an up-and-coming suppressor company known as Advanced Armament Corporation (AAC) took an interest in this round.
AAC was soon bought by Remington Arms and they worked hand in glove with Remington to produce a new round to address perceived pitfalls regarding the US Military’s 5.56 NATO round.
Designers and engineers at both AAC and Remington Defense altered the dimensions of the 300 Whisper by trimming and re-necking 5.56 NATO brass as the parent case instead of 221 Fireball or 222 Remington. They submitted the new cartridge specs to SAAMI (Small Arms Ammunition Manufacturers Institute) and CIP (Permanent International Commission for the Proof of Small Arms) for standardization and called this new round 300 AAC Blackout by CIP and 300 BLK by SAAMI.
These changes actually made the round more versatile by allowing the 300 Blackout to fit and function in standard AR-15 magazines intended for 5.56 and to utilize the rifle’s standard bolt carrier group. The only actual part change for a conversion would be replacing the barrel.
It should be noted that 300 Blackout and 300 Whisper are fully interchangeable with regard to barrels, rifles, pistols, loading dies, loading components and loading specifications.
The 300 Blackout cartridge has made huge inroads into the shooting world since its inception. Fans of the 7.63X39 cartridge gained an equivalency in the AR platform without having to reinvest in magazines for another platform. Most significant was its impact in the realm of suppressed shooting.
When it was known as 300 Whisper, the cartridge was mostly chambered in AR-15 rifles and Thompson Center Contender single shot rifles and pistols. It stayed this way when 300 Blackout first rolled out, but grew to include the Remington 700 rifle, Harrington Richardson’s Handi-Rifle, Ruger’s Mini-14, Steyr AUG and numerous other semiautomatics, single shot and bolt action rifles and pistols.
Both versions of 300 Blackout, supersonic and subsonic, have gained popularity with hunters and sportsman on medium to large game such as white-tailed deer, black bear, feral fogs and coyotes.
Likewise, 300 Blackout has become hugely popular among target shooters. In October 2011, Daniel Horner of the US Army Marksmanship Unit (now with SIG Sauer’s shooting team) won his 4th USPSA (United States Practical Shooting Association) Multi-Gun National Championship title shooting a rifle chambered in 300 Blackout.
Although the round has great potential for the law enforcement community, not very many agencies have adopted it as of this writing.
This caliber may not become the newest service rifle caliber across the board, but it has been used by Special Operations Forces in several branches of the US Military with success. The weapon of choice for US SOCOM (Special Operations Command) is a SIG Sauer MCX Rattler in a PDW (Personal Defense Weapon) configuration with a 5.5-inch barrel.
It has also been adopted by the Dutch Royal Marines Maritime Special Forces.
300 Blackout has an overall length of 2.26-inches and an overall case length of 1.36-inches. It uses a .30 caliber bullet, and the case has a capacity of 19.3 grains.
The recoil of 300 Blackout is comparable to a mild 7.62 x 39 or 30-30 Winchester round
Depending upon the load data and the barrel length of the weapon, 300 Blackout can generate between 400- and 1700-foot pounds of muzzle energy.
SBR offers a great variety of special purpose subsonic ammunition for 300 Blackout ammunition. Of particular note for the hunters is a 194-grain Maximum Expansion load that offers an impressive wound channel when it expands inside the target.