AR15 Barrel Twist Rates, Explained
- By Patrick Combs
- Mar 1, 2023
Whether you’re new to modern sporting rifles or an experienced shooter, understanding how AR15 barrel twist rates impact your shooting accuracy is crucial.
In this article, we’ll explain what barrel twist rates are, where to find barrel twist rates, and discuss what you should know about AR15 barrels and AR15 ammo. We’ll get into a little bit of physics but we promise to keep it short and simple. Keep reading for barrel twist rates explained!
What are Barrel Twist Rates?
When it comes to storing firearms, one of the first things you need to consider is air temperature and moisture. The wrong temperature or too much humidity can damage your guns.
The ideal temperature for storing guns is approximately 70 degrees Fahrenheit. You’ll want to keep your guns in a temperature-controlled environment for optimal results. Relative humidity for gun storage should be between 45 to 55 percent.
Even a small amount of moisture can rust a gun and cause internal parts to deteriorate. To prevent excess humidity, you can use a dehumidifier or silica gel packets to manage moisture levels.
Don’t store your gun in the holster or the cardboard box it came in. Storing guns in cases or rugs is also not recommended. The lining can absorb moisture from the air, accelerating the rusting process.
Only use gun safes or containers that are explicitly designed for use with guns and ammunition. If you can afford a firearm, you can invest in items for proper firearm protection for secure gun storage.
Twist rate is the speed of the bullet’s spin. Some of the most common AR15 barrel twist rates for ARs chambered in 5.56mm NATO or .223 Rem are 1:7, 1:8, and 1:9. The first number is one full rotation of a bullet, and the second is how many inches of barrel length the bullet needs to travel to make that full rotation. So, for a 1:7 twist rate, the bullet is moving 7 inches down the barrel before it makes one full rotation.
Slower barrel twist rates cause bullets to yaw because they don’t spin fast enough to stabilize properly. A barrel twist rate that is too fast can cause similar problems for lighter bullets. Having the right ammo for your gun is key. Generally, longer bullets tend to be heavier and need a faster twist rate to prevent stability issues. Shorter bullets are usually on the lighter side and don’t need as much spin, so slower twist rates work.
How Fast is a Bullet?
There are three main factors that affect the speed of a bullet: the bullet’s grain, barrel length, and cartridge. Bullet grain is essentially the weight of the bullet. It’s harder for a heavier bullet to accelerate, so if everything else is equal a lighter bullet will travel faster.
When it comes to barrel length, the longer the barrel is, the more time the bullet has to accelerate. A longer barrel increases bullet speed. Cartridge is the type and amount of propellant behind the bullet. The cartridge in relation to the bullet weight will determine the bullet’s speed. Bigger cartridges typically move faster, but not always.
You’ll want to consider all three of these factors when choosing AR15 barrels and AR15 ammo. Combining the wrong bullet grain and barrel length can negatively impact your shooting accuracy. Be sure to follow all manufacturer recommendations for your AR when selecting ammo.
For example, although the .223 Rem and 5.56mm NATO cartridges are often treated as interchangeable, this can become dangerous in some circumstances. The two rounds are similar in size, but they aren’t exactly the same. Most of the time .223 ammo will chamber and fire in a 5.56, and the opposite is also true. But it’s important to know that 5.56 ammo is loaded with a much higher pressure than .223 Rem. 5.56mm chambers are also built to handle that increased pressure, while .223 chambers typically are not.
.223 Rem chambers also have a shorter leade, which is the distance from the mouth of the cartridge to the point where the bullet meets rifling, and a steeper angle than 5.56mm chambers. The 5.56mm was designed to be used with a longer leade and a shallow angle to increase the bullet’s velocity. If everything else is the same, a shorter leade causes increased pressure compared to a longer leade.
Since this AR15 ammo is similar in size, it can be challenging to find out if it’s .223 Rem or 5.56mm NATO if you don’t have the packaging. In this case, you can look at the stamp on the base of the bullet. It will say 5.56x45mm or have 2-3 letters + 2-3 numbers + with a cross inside a circle if it is 5.56mm. .223 will often include “223” on the stamp.
AR15 Barrel Twist Rates
For AR15 rifles, the most common chambering is .223 Remington or 5.56 NATO. If you’re wondering where to find barrel twist rates, you’ll want to check the barrel markings on the gun. AR uppers can be changed easily, so the chamber or caliber might not match the markings on the lower.
Here’s an overview of common AR15 barrel twist rates in the 5.56 NATO/.223 Rem chambering.
1:14 Twist Rate: This is not a common barrel for recently manufactured AR15s, but you may see it from time to time. It’s best for bullets up to 50- and 52- grains, which mostly fall into the varmint and target shooting categories.
1:12 Twist Rate: Works well for bullets in the 55- to 60- grain range. Most effective for hunting coyotes or prairie dogs with lightweight bullets.
1:10 Twist Rate: This works well for lighter bullets up to 69 grains.
1:9 Twist Rate: If you prefer to use heavier bullets, a 1:9 twist rate is fast enough to stabilize most. It’s not so fast that it causes problems with 55-grain bullets and it can handle most traditional bullets up to 75 grains.
1:8 Twist Rate: This is one of the most versatile twists for a 16-inch general use carbine. It stabilizes bullets up to 80 grains.
1:7 Twist Rate: Stabilize bullets up to 90 grains. This is the barrel rate twist used by the military since the 1980s. It works well for carbines with very short barrels, handling 70- to 77-grain bullets with ease.
AR15s chambered in 5.56 NATO can safely handle a wide range of bullets with a 1:7 or 1:8 barrel twist rate, which is why these tend to be among the most common AR15 barrel twist rates.
Find AR15 Barrels, Ammo, and More
Green Top Sporting Goods has a wide range of AR15s, ammo, and accessories to choose from. To find barrel twist rates by manufacturer, check out our detailed product listings. If you have any questions about AR15 barrel twist rates, we’re here to help. Order online or shop in store today.