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  • Post last modified:April 9, 2023

Let's break down 6.5 Grendel vs 300 Blackout in detailed specs in this article. Overall, the 6.5 Grendel is better suited for longer range shooting, while the .300 Blackout is better suited for close to medium range shooting and suppressed applications.

They are two very different calibers.

6.5 Grendel VS 300 Blackout - Key Differences

65 grendel vs 300 blackout

Both the 6.5 Grendel and the .300 Blackout are popular cartridges with different performance characteristics.

The 6.5 Grendel has a flatter trajectory, greater velocity, and more energy at longer ranges. It's known for its accuracy and ability to take down medium-sized game.

The 6.5x39mm cartridge contains a .224" bullet with extra powder in the casing, which gives it velocities similar to 5.56 NATO and .223 Remington (about 2,500 to 2,900 FPS) but with a heavier bullet that has a higher ballistic coefficient. 

The .300 Blackout has a heavier bullet, making it better suited for short to medium ranges. It's popular for its ability to be suppressed and its compatibility with the AR-15 platform.

6.5 grendel hornady

6.5 Grendel vs. 300 Blackout Dimensions


300 Blackout

6.5 Grendel

Bullet Diameter



Neck Diameter



Base Diameter



Case Length



Overall Length



Standard Bullet Weight

110 - 220 gr

90 - 130 gr

The 6.5 Grendel measures 2.26 inches in overall length and can handle a pressure of up to 52,000 psi. Its case length is 1.5 inches, its neck diameter is 0.471 inches, and its bullet diameter is 0.264 inches. The recommended powder charge for the 6.5 Grendel ranges from 20 to 28 grains.

The .300 Blackout has a case length of 1.368 inches and an overall length of 2.26 inches, which is the same as the 6.5 Grendel. It can handle a maximum pressure of up to 55,000 psi.

The .300 Blackout bullet diameter is .308 inches, which is larger than the 6.5 Grendel's bullet diameter of .264 inches. The neck diameter of the .300 Blackout cartridge is .338 inches.

Recommended powder charges for the .300 Blackout depend on the specific bullet weight and type being used, but generally range from 9 to 17 grains for subsonic rounds and 15 to 30 grains for supersonic rounds. The cartridge is versatile in that it can be loaded with a wide range of powders, making it adaptable to different applications and preferences.

6.5 Grendel VS 300 Blackout Effective Range

The 6.5 Grendel boasts a flatter trajectory than the .300 Blackout, thanks to its higher ballistics. This advantage becomes more pronounced at longer distances, where rifles chambered in 6.5 Grendel will outperform those chambered in .300 Blackout by a significant margin.

While the .300 Blackout typically drops off at around 300 yards, the 6.5 Grendel can maintain its accuracy beyond 600 yards. This extended effective range is particularly important for ethical hunting, as it allows for more precise shots and ensures a clean kill.

Additionally, the 6.5 Grendel excels at long distance shooting, with an effective range of over 800 yards, compared to the .300 Blackout's range of 400 yards. 

6.5 Grendel VS 300 Blackout Ballistics


Referenced Sierra Bullets

The 6.5 Grendel's 123 grain bullet boasts a muzzle velocity of 2,580 fps, muzzle energy of 1,818 ft lbs, and a ballistic coefficient of 0.506. This allows it to maintain supersonic velocity at 1,000 yards and retain 400 ft lbs of energy.

At 200 yards, the .300 Blackout falls below the commonly accepted minimum energy required for hunting whitetail, while the 6.5 Grendel maintains its energy and velocity up to 300 yards, exceeding the .300 Blackout's muzzle velocity.

long range targets

This makes the 6.5 Grendel the clear winner ballistically, particularly at longer ranges where the .300 Blackout struggles past 150 yards.

In closer ranges, both cartridges have sufficient energy to dispatch mid-sized soft targets, with the .300 Blackout holding onto its initial velocity within those ranges.

Nevertheless, the 6.5 Grendel starts and maintains its velocity better than the .300 Blackout, resulting in less trajectory degradation at longer distances, making it the superior choice overall.


6.5 Grendel Vs 300 Blackout Muzzle Velocity & Energy

Bullet Velocity (Muzzle)2,580 ft/s2,175 ft/s
Bullet Velocity @ 100 yds2,410 ft/s1,932 ft/s
Bullet Velocity @ 200 yds2,246 ft/s1,708 ft/s
Bullet Velocity @ 300 yds2,088 ft/s1,505 ft/s
Bullet Energy (Muzzle)1,818 ft⋅lb1,313 ft⋅lb
Bullet Energy @ 100 yds1,585 ft⋅lb1,036 ft⋅lb
Bullet Energy @ 200 yds1,377 ft⋅lb810 ft⋅lb
Bullet Energy @ 300 yds1,191 ft⋅lb609 ft⋅lb
Usage @ 0 ydsLarge GameMedium Game
Usage @ 100 ydsLarge GameMedium Game
Usage @ 200 ydsMedium GameSmall Game
Usage @ 300 ydsMedium GameSmall Game
300 blk aac

Velocity is an important factor when comparing these two cartridges. As seen in the chart, the 6.5 Grendel has a higher bullet velocity compared to the .300 Blackout, even when bullets of similar weight are used.

For example, at the muzzle, the 6.5 Grendel is moving 405 ft/s faster than the .300 Blackout. As the range increases, the difference becomes even more significant, with the 6.5 Grendel moving 583 ft/s faster at 300 yards.


These design differences highlight the varied purposes of each cartridge. The 223 Rem and 5.56 NATO aim for high velocity with low recoil, relying on bullet fragmentation and hydrostatic shock, while the 6.5 Grendel prioritizes delivering large amounts of kinetic energy into the target with heavier bullets.

Keep in mind that barrel length greatly impacts muzzle energy and velocity. Manufacturers often provide ballistic data based on proofing barrels - typically 20” for 223/5.56 and 24” for 6.5 Grendel.

6.5 Grendel VS 300 Blackout Cost

ammo shelf at the store

When it comes to cost-effectiveness and availability, the .300 Blackout outperforms the 6.5 Grendel. While the 6.5 Grendel is a good value for its performance in the AR platform, the popularity and success of the .300 Blackout, along with the economics of the materials used in the two cartridges, mean that the .300 Blackout is considerably cheaper and more widely available.

At the time of writing, a box of 20 rounds of 6.5 Grendel ammunition can cost anywhere from $20 to $40, depending on the brand and type of bullet. In comparison, a box of 20 rounds of .300 Blackout ammunition can cost between $15 and $30 on average.

For those concerned about their cost per round, particularly if they do not handload their ammunition, the .300 Blackout is the better option. While the 6.5 Grendel has its advantages in terms of performance, shooters should consider their budget and needs when selecting a cartridge for training and practice.

6.5 grendel ballistics

Referenced The Firearm Blog

300 AAC Ballistic Chart

300 blackout ballistics

Referenced The Firearm Blog

Hunting Applications

olight odin turbo deer id

While the .300 Blackout may be a better option for close-range hunting with a suppressor, such as hog hunting at night, it is generally not recommended for game larger than whitetail or at distances greater than 150 yards.

In these scenarios, the 6.5 Grendel is the more versatile option and is capable of taking down larger game at longer ranges.


Here, the 6.5 Grendel wins. It has the ballistic coefficient that enables it to keep slick and not drop much to ranges out to 1000 yards. This has been proven.

Some shooters call it an equivalent to the .308 at long range but with less recoil, and that’s how it was designed. 

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