.300 Blackout Barrel Length Guide & Tips

What is 300 blk good for? That's really what everyone wants and needs to know — why spend more money on an expensive caliber for an AR15 build when you could just shoot .223 or 5.56 NATO?

What caliber is 300 BLK? This caliber is a type of 30-caliber rifle cartridge and it was designed to deliver a bigger punch on impact while using shorter-length barrels. Additionally, 300 blk has a lesser chance of overpenetration making it the go-to choice for several special operations units that engage in close-quarter combat.

For civilians - that makes 300 blk a great choice for home defense, target shooting, and even some white-tail deer or boar hunting.

.300 BLACKOUT SPECS THAT MAKE IT WORTH YOUR WHILE

Suppressor use is where the 300 blk especially shines. When using subsonic ammunition, an AR15 chambered in 300 Blackout has extremely soft recoil, helping you to get more hits on target (and likely faster too).

What that also means is if you wanted to be more budget-friendly, a single AR15 lower could be paired with multiple complete uppers chambered in different calibers which would save you a pretty penny.

For those that don't plan on running a suppressor and really want to take full advantage of this caliber, the .300 Blackout also comes in supersonic options. Using higher-velocity bullets can increase the shooting range slightly, which is beneficial too.

Ballistically speaking, a rifle or carbine chambered in 300 Blackout can certainly be considered a worthy firearm as it gives you the stopping power of an AK but in an AR platform. If you're planning on doing some hog hunting there are some great ammo options out there for you to choose.

These are some that we would use:

BARREL LENGTHS THAT WORK FOR THE AAC .300 BLACKOUT

The .300blk pdw version of the Daniel Defense DDM4 PDW. Photo Source: Daniel Defense

Though there is a lot of talk among gun enthusiasts about the nine-inch sweet spot of barrel length when it comes to the .300 Blackout, the ammo works well with different variations of barrel lengths and uppers.

Without unnecessary weight and length implications, the gun barrel's length is used to produce room for the gunpowder in your ammo to burn out before the bullet exits. A longer barrel, because of its increased surface area, provides more room for cooling in instances where you shoot continuously.

The shorter a gun barrel, the more the gas expulsion at the muzzle equals a relatively louder sound every time you shoot. To counter this, of course, there is always the option of sticking a silencer onto the muzzle. In instances where that is not an option, however, you can always go long or brace yourself for those loud blasts with every shot.

In theory, a longer barrel offers more room for bullet expulsion. But if the amount of gunpowder to be burned is held constant, the length starts becoming a drawback. And since you can't stuff more gunpowder into your ammo, it's essential to ensure you do not go too extreme on the barrel length.

On the flip side, having a shorter barrel allows for easier close-combat shooting, which would otherwise be a challenge if you had a nine-inch barrel. That's why you might see a lot of .300 blk pdw (personal defense weapon) options on the market.

For hunting expeditions or other long-range requirements, the .300 AAC Blackout has a maximum effective range of approximately 460 meters. However, this maximum effective length is determined by the barrel's length, and the 460-meter distance is achieved by a nine-inch barrel.

The barrel also plays a role in the drop rate of the bullet. For instance, the nine-inch barrel has a 100-inch drop at 410 meters, while a 16-inch barrel has a drop of a 100 inches at 440 meters.

HOW DO YOU BUILD AN AR-15 IN THE .300 BLACKOUT?

One important consideration before you set out to build your AR-15 in the .300 Blackout is knowing the scope of usage of your gun. Will the gun be a 'do it all' for long-range or short-range shots?

When picking out a muzzle for your assembly, keep in mind the muzzle's compatibility with available suppressor fittings. Your muzzle choice should also be in consideration of the flash produced and the muzzle rise with every shot.

When picking an upper for the setup, you can go either with a T-Marked or a Non-T-Marked, depending on your personal preference. For a more economical build experience, getting a full lower build kit will save you some bucks.

The build kit comes with well-documented manual instructions for putting together the firearm, along with well-labeled parts, which are all individually packaged.

DO SPECIAL FORCES USE THE .300 BLACKOUT?

As a testament to the efficiency of the .300 AAC Blackout, several military units across the world, including the Netherlands, the United Kingdom, and the United States, have adopted it. With the same profile as a M4 rifle, but a shorter barrel, many operators get to use the same manual of arms while appreciating the high stopping power of the 300 Blackout in close-combat engagements compared to other ammunition issues.

CAN A .300 BLACKOUT BARREL SHOOT 556?

Even though the .300 AAC Blackout's design implementation was based on the shell casing of the .556, the latter cannot be shot from the barrel of a .300 Blackout.

HOW DOES THE 350 LEGEND COMPARE TO THE .300 BLACKOUT?

Compared to other ammunition like the 350 Legend, the .300 AAC Blackout is more effective in taking long-range shots. It also has a great barrel life, which means it can go for long periods and operate effectively under varying conditions. The .300 Blackout's rather streamlined shape allows for it to have magazines with minimal curvature, which makes them less prone to jam.

FROM WHAT DISTANCE WILL A .300 BLACKOUT KILL A DEER?

Can you hunt with 300 BLK? Yes! This caliber is quite effective when hunting for animals like wild pigs, deer, or varmints. For the best results, we suggest that you use recommended hunting ammunition variants of the .300 Blackout (like the 125-135 grain range).

These rounds can work well in taking out deer at distances of up to 300 meters, depending on who is handling the rifle and the shooting conditions they're in.

In matters of velocity comparison, different barrel lengths for the .300 Blackout sit within the 25-50 feet per second per barrel velocity rule that governs most firearms.

For example, with a 10.5-inch barrel, the .300 Blackout clocks an average velocity of 2200 feet per second. While on a 16-inch barrel, it reaches speeds of approximately 2400fps.

Having a longer barrel also provides more time and surface for the bullet to stabilize from the point of firing to the point where it exits the muzzle. This ensures that the bullet maintains a more accurate and precise trajectory upon exit and improves the target-inaccuracy issue.

A longer barrel also offers a long line of sight for you to better aim your rifle even if the rifle is not equipped with sight extensions.

A big factor of consideration when picking a rifle, its barrel length, or ammunition is the type of target you wish to use it on. Though the .300 Blackout was designed to offer the best results in close-range targets, you can use it for long-range targets as well.

For long-range targets, barrel lengths of up to 16 inches are available. Nothing further than that is as effective since the gunpowder burning would be inefficient in the spare room. We still wouldn't plan on engaging anything at 500 yards and would stick to engagements under 300 yards.

IS A 16-INCH BARREL GOOD FOR THE .300 BLACKOUT?

A 16-inch barrel is the longest available barrel for the .300 Blackout, and it is quite effective when it comes to longer-range targets. It's definitely an oddball choice, but some offer those barrel lengths.

The length of a barrel also dictates the rifle's twist rate and thus the bullet as it travels down the barrel. The twist rate is when the bullet twists within a barrel once fired, which helps keep it at a high velocity and helps maintain accuracy.

A longer barrel has a slower twist rate and provides more power and accuracy, which is better for long-range targets. A longer barrel, because of its increased surface area, provides more room for cooling in instances where you shoot continuously.

Whether you decide to go long or short on your barrel is entirely a matter of what you are shooting at and where the shooting is taking place. If it's inside your house in home-defense scenarios, a short barrel will allow for better maneuverability.

And if you are out in the wild shooting at some long-range game, a longer barrel will give you both the power and accuracy advantage. But all things considered, the .300 Blackout will surely deliver whenever it's put to the task.

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