The .300 Blackout Round Explained
If you’ve done any shopping online here at Thunder Tactical or been involved in the gun community for even a short period of time, you may have encountered the term “300 blackout,” but this term is fairly new even to experienced shooters, and you may not yet understand just what it means. Keep reading to learn the basics of the .300 blackout round and how to prepare your rifle to shoot it.
What is the .300 blackout round?
During World War II, Soviet Russia began to develop the 7.62x39mm rifle cartridge for use in their military carbine rifle (replaced by the AK-47 in the ‘50s). This cartridge was designed to serve many purposes. The Soviets wanted a rifle round that would be equally as effective in semi-automatic, selective fire, and light machine gun use. In response, the United States decided to develop their own cartridge based on the 7.62x39 but in an AR-15 platform. The resulting cartridge is the .300blk, about as long as a .223 or 5.56 round but with a much larger bullet, lower neck, and many internal differences. The .300blk has very similar ballistic performance to the 7.62x39mm cartridge it was based on but with a lighter bullet, making it the ideal round for a wide variety of applications. Various .300blk rounds make this cartridge just as effective as a hunting rifle as it will be for shooting subsonic suppressed ammunition.
Can I Shoot .300 blackout out of my AR-15?
Have you ever wondered why shotgun shells are color-coded? Perhaps you’ve noticed the many colors of shotgun shells but never even realized there was a reason for this. In fact, there is a very good reason for this: loading the wrong size shotgun shell into your shotgun can have disastrous consequences. The same can be said for the carbine rifle (and every other type of firearm ever).
The .300 blackout round was designed for use in the AR-15 platform, using AR-15 magazines, but you won’t have much luck (read: for the love of guns, DO NOT do this) loading a .300blk round into your .223/5.56 upper. While these rounds are similar in length, the .300blk shoots a 30mm caliber bullet instead of a 22mm caliber bullet, which means the frontal bullet area is almost 90 percent larger than the frontal surface area of the .223/5.56 bullet. In order to shoot .300blk out of your carbine rifle, you’ll need to replace the barrel/upper with the properly sized parts, or you could end up having to replace your entire rifle. Check out the linked blog to learn what happened just three lanes down from this firearms blogger when a shooter loaded .300blk ammo into an .223 upper, chambered a round, and attempted to fire.