Before we start the side-by-side contrast and comparison between rifle ballistics’ 300 Blackout and 5.56mm NATO, let’s first dive into each of its humble beginnings.

AAC’s take on the .30-cal

Despite being a new caliber, the .300 Blackout has quickly risen to prominence in the last 20 years. It’s been popularly used in Special Operations and other specialized military units due to its ability to suppress the round well with impressive ballistics. Hunters started using these, too, boosting their ability to sneak around their prey.

Advanced Armament Company (ACC) designed the .300 Blackout (300 BLK) in the late 2000s to meet the growing demand for ballistics that can offer less sound noise level. At the same time have more capable firepower and compatibility with the rifles such as M4s and AR-15s.

(Screenshot from Hoplopfheil/YouTube)

Its conception initially aimed to achieve similar ballistics to the 7.62x39mm, but with enhanced “stopping power” and can perform in a subsonic velocity using a short-barreled rifle.

“A military customer wanted a way to be able to shoot .30-caliber bullets from an M4 platform while using normal bolts and magazines, and without losing the full 30-round capacity of [the] standard magazine,” said Robert Silvers, director of research and development for AAC.

“They also wanted a source for ammunition made to their specs. We could not have just used .300-221 or .300 Whisper because Remington is a SAAMI company, and will only load ammunition that is a SAAMI-standard cartridge. We had to take the .300-221 wildcat concept, determine the final specs for it, and submit it to SAAMI. We did that, and called it the .300 AAC Blackout (.300 BLK).”

At the start of a new decade, the 2010s, the production for the 300 Blackout commenced. Aside from civilian consumers, the 300 BLK has been inducted into military service in the armed forces of the Netherlands, the United Kingdom, and recently in the United States, particularly in the special operations command. In addition, the US forces selected the .300 Blackout as one of the ballistics for its self-defense weapon, the SIG Sauer MCX Rattler, allowing the firearm to be silently powerful while remaining compact.

300 BLK Technical Specs

  • Parent case: .221 Fireball/.223 Remington
  • Case type: Rimless, bottleneck
  • Bullet diameter: 0.308 in (7.8 mm)
  • Neck diameter: 0.334 in (8.5 mm)
  • Base diameter : 0.376 in (9.6 mm)
  • Rim diameter: 0.378 in (9.6 mm)
  • Case length: 1.368 in (34.7 mm)
  • Overall length: 2.26 in (57 mm)
  • Rifling twist: 1-8″ (203 mm)
  • Primer Type: Small rifle
  • Maximum pressure (SAAMI): 55,000
  • Maximum pressure (CIP): 56,565
  • Maximum CUP: 52,000 CUP

5.56mm Time-Tested

Meanwhile, 5.56mm has been around since the 1980s, when it was designed by FN Herstal a decade earlier. It was also derived from the .233 Remington, was widely used by law enforcement, and was generally accepted by gun enthusiasts and athletes. Its wide range of availability and low cost earned it a place among home defense rifles.