The 300 Blackout (pronounced “three-hundred black out”), officially referred to as the 300 AAC Blackout or the 300 BLK, or 7.62×35, is just a rifle cartridge made to be fired through AR-15 rifles with shorter-than-average barrels.
Technically, the sole proper names for the cartridge are the 300 AAC Blackout or 300 BLK, but most people reference it really while the 300 Blackout, so Used to do exactly the same in this short article for the sake of simplicity.
A cartridge, also called a round, identifies a style for a how a case (the brass shell that holds the gun powder) and a bullet all fit and function together. Thus, the 300 Blackout cartridge identifies a specific bullet and case combination.
The three cartridges on the left are different kinds of 300 Blackout ammo, followed by way of a 5.56 cartridge and a 7.62×39 cartridge on the right.
The “300” in 300 Blackout stands for .30-caliber, which is a way of measuring the diameter of the barrel a bullet was created to be fired through. One caliber is one hundredth of an inch, and calibers are written as decimals of 1 inch, like .30-caliber. Hence, .30-caliber is about one third of an inch.
You will want to call it the 30 Blackout, then, since it fires a .30-caliber bullet?
Because 300 sounds stronger than .30, which explains why many companies reference .30-caliber bullets as “300-” something and other, just like the 300 Winchester Magnum and 300 Norma Magnum hunting cartridges—all of which fire .30-caliber bullets.
You'll also see bullet widths measured in millimeters (mm), and the width of the 300 Blackout bullet calculates to 7.62 mm. For this reason the 300 Blackout is also called the 7.62×35, which corresponds to its bullet width and case length in mm, respectively.
“Blackout” is just a product name of the business who invented the cartridge—Advanced Armament Corporation (AAC)—who designed it at the behest of the military with three main goals in mind:
It must be equally or stronger than the 7.62×39 cartridge (AK-47 ammo) when fired from 9-inch barrel.
It should work in AR-15 rifles and magazines, with just a change of the barrel required to make it operational.
It should work reliably when working with low-powered (subsonic) or high-powered (supersonic) ammo with or without a suppressor.
The principal goal was to produce a cartridge for special forces units that might be as quiet as suppressed 9mm ammo fired from an MP5SD, but with greater lethality than 9mm and 5.56 ammo.
At the time, the U.S. military was embroiled in multiple large scale urban battles across Iraq, and many special forces units had started using short-barreled rifles to make it easier to maneuver when fighting house-to-house.
As you'll learn later in this short article, while this does make rifles much simpler to use in confined spaces, additionally, it neuters the power of the 5.56 cartridge.
Thus, Kevin Brittingham, the founder and CEO of AAC, tasked one of is own chief engineers, Robert Silvers, to find a solution.
To meet up these requirements, they looked to the same cartridge called the .300 Whisper, that was produced by noted firearms cartridge designer J.D. Jones. AAC took the .300 Whisper, made slight modifications to the case and bullet to boost reliability, accuracy, and performance, and birthed the 300 Blackout (there's more to this story, but that's the long and short of it).
Jason Imhoff then drafted the specifications for the cartridge that will eventually be approved by SAAMI.
The cartridge on the left is the 5.56, usually the one at the center is the 300 Blackout, and usually the one on the right is the 7.62×39.
The main reason the cases of the 5.56 and 300 Blackout are so similar is because both cartridges need to suit in exactly the same gun. The 300 Blackout was designed to be used with exactly the same bolt—the area of the gun that grabs the trunk of the cartridge, pushes it in to the chamber, and extracts it after firing—while the 5.56, meaning both cases need to have almost exactly the same dimensions.
Even though the cases are similar, the 300 Blackout case is shorter, which reduces the amount of gunpowder that will fit in case by about 25% versus the 5.56. On the plus side, though, it can also hold a weightier, wider bullet than the 5.56 and still work in a AR-15.
Before we go any further, it's worth spending just a moment to obtain acquainted with the 5.56, as we'll be comparing it to the 300 blackout bulk ammo throughout this article.
The 5.56 (pronounced “five-five-six”), also referred to as “5.56×45 NATO” or “the 556,” was designed in 1980 to utilize the AR-15 rifle and is the conventional rifle cartridge for all NATO forces, like the United States, England, Germany, and other countries.
The 5.56 is based on and almost identical to a tube invented in 1959 called the .223 Remington, or “223,” so you'll often see them lumped together in bullet comparisons (“5.56/.223 vs. 300 Blackout,” for example).
They aren't exactly the same, but they've nearly exactly the same performance and may be considered as exactly the same cartridge as it pertains to ballistics comparisons.
We'll talk more about how the 5.56 and 300 blackout bulk ammo stack against each other in a moment.
