The 300 Blackout has become a popular AR platform option due to how easy it is to convert an existing 5.56/.233 build with a simple barrel change. It also is incredibly versatile and a fun cartridge to shoot due to its lower recoil and dependable accuracy.
Choosing a barrel for your 300 BLK shooting needs depends on your use of the firearm and the weight of the cartridge you plan on shooting. Part of this choice involves the rifling, or barrel twist that works to stabilize your bullet when you shoot. Take a look at a quick breakdown to better understand the 300 Blackout 1-7 vs 1-8 twist rate to determine which is the best option for your needs.
What’s The Difference Between a 1-7 and 1-8 Twist Rate?
The rifling found on the inside of a barrel is specific to how many times a bullet rotates in reference to the twist ratio. For example, a bullet will rotate one full time every 7 inches of barrel length in a 1-7 rifled barrel, and one full time every 8 inches of barrel length in a 1-8 rifled barrel.
For the most part, you might not find as many 1-8 twist options for a 300 Blackout, simply because the heavier bullet options are much more popular for what the firearm is designed for. However, that doesn’t mean they don’t exist. The ratio simply refers to how many rotations the bullet makes in reference to the twist- which works on the stabilization of the bullet as it leaves the barrel.
What is Barrel Rifling?
First, let’s explain what barrel rifling is and why it is important. Putting a spin on any projectile makes it more accurate and stable (think about throwing a football at a target), and this was quickly understood when early gunsmiths were looking for a way to make every shot count. The idea was born in Germany during the 1500s, but wasn’t widely applied until the early 1800s. Regardless, the idea caught on quickly after that- and the art of matching the proper cartridge with twist rate is important for your shooting experience.
The twist rate in a barrel can be created one of three ways: cold hammer-forged, cut rifling, or button rifling. Cut and button rifling is a much more common occurrence in the US, and both are quite effective in creating the grooves your bullet will spin along. As mentioned above, the rate of twist is defined by how many times a bullet completes a full rotation as it spins down the barrel. This ratio is expressed as 1: to the number of inches it takes to complete a rotation. The lower the number, the faster the twist.
300 Blackout Popularity and Uses
AR platform rifling generally falls between 1:7 and 1:12, and knowing how this affects your shooting style is particularly important when you are modifying existing AR builds to accept something other than it was originally built for.
A 300 BLK is a popular round for its versatile uses. It can be shot from both short and long-barrelled firearms, and is considered an accurate choice in both subsonic and supersonic options. This lends itself well to home defense, hunting, and even performance competitions, such as a 3 gun match. Thus, knowing your rifling pattern in preparation of shooting is an important step to ensure you are choosing the best bullet for what you have.
Bullet Weight Explained
The basic weight of a bullet is expressed as the bullet grain. One grain equals 1/7,000 pound and refers to the weight of the projectile firing from the barrel. There are pros and cons to shooting both lighter-weight bullets vs heavier grains, and you should always know what is offered in the caliber ammo you have chosen. For example, the 300 BLK is commonly found between 110 gr and 220 gr options.
Lighter bullets offer more speed and a straighter, more accurate trajectory for long-range shooting, but this also means it can be more easily blown off course and will not damage the game as efficiently. Therefore it isn’t the best choice for certain hunting scenarios, especially larger games such as deer or hogs at a longer distance. This is because heavy grains provide better target penetration, but might not provide the same accuracy over long distances since its trajectory will drop more the further it travels.
300 BLK Bullet Weight and Ideal Twist Rates
Supersonic or lightweight choices will often do best with a 1:8 ratio, while anything heavier than 80 grains will generally work best with a faster rate of twist. Since a 300 BLK cartridge is on average heavier than 80 gr, it will shoot best with a 1:7 twist in order to provide the most efficient stabilization and accuracy.
You certainly can shoot various weights through less than ideal rifling; you simply won’t get the maximum effectiveness out of the bullet. For example, you can shoot a lighter bullet through a 1:7 twist rate, but it will over-stabilize it and will not be as accurate at longer distances. A 1:8 ratio with the heavier 300 BLK bullet isn’t the best use of its effectiveness either, and will work against its overall potential energy and velocity when leaving the barrel. However, for close-range targets, this won’t make much of a difference.
To Wrap It Up
Due to the bullet weight offered in a 300 BLK and its versatile shooting style, you will find both 1:8 and 1:7 twist ratios to be commonly offered. The 1:8 options are generally found in the shorter barrels between 7.5 and 10.5 inches to shoot supersonic rounds more accurately over longer distances, while a 1:7 twist will be a better choice for longer barrels to provide the velocity a heavier subsonic bullet requires for accuracy. If you want a more detailed breakdown of how the math works with this all, check out the calculations and twist rate charts.
The bottom line is, you need to consider your own shooting purposes and decide which cartridge you prefer for your specific needs- and choose your barrel based on that need. However, for heavier bullets used for hunting purposes, the 1:7 is going to be the best twist rate for 300 Blackout.
We’d love to hear what your own thoughts are on rifling differences for the 300 BLK platform, and which you prefer- and why.