.300 Blackout Guide: Best Barrel Length, Build Tips & More (2024)

History of the .300 Blackout

Developed in 2009 by the Advanced Armament Corporation or AAC, the .300 Blackout is regarded as a round that gives top-class performance when compared to similar calibers. The development of the .300 Blackout was a joint effort between AAC and Remington Defense, and this was to produce a replacement for the 5.56 NATO.

With the War on Terror on the rise at the time, the development was also motivated by the need to produce a .30 caliber cartridge that would produce better results in combat than the 5.56mm rounds that were currently in use. Avoiding the logistical nightmare that would have been to replace the military's standard issue rifle during an ongoing war, the .300 Blackout was designed to be compatible with the M4 system. This adaptability to the existing rifle specifications was made possible by the fact that the designers and engineers chose not to go down the path of building up from scratch. Instead, they built the round from the M4-compatible 5.56mm cartridge.

The .300 Blackout Specs That Make It Worth Your While

The .300 AAC Blackout is designed as a variation of the older .300 Whisper ammunition. Compared to other bullets, a .300 Blackout is a 30-caliber bullet in a .223/5.56mm shell casing. The distinction means the round can fit into an AR magazine, an AR upper built for the .300 Blackout, and an AR lower. This means that one gun can serve as two just by switching the uppers.

Built for use with suppressors but still maintaining subsonic speeds, the .300 Blackout is designed to penetrate heavy barriers while still maintaining an overall manageable weight profile. With a relatively convenient recoil, the .300 AAC Blackout is known for giving users an easier time staying on target. It gives an almost negligible muzzle rise while shooting, meaning most of the energy produced during recoil comes back to the shooter's shoulders. Though the muzzle rise and recoil forces are not entirely negligible, they are not enough to affect follow-up shots for the shooter.

Standardized with SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) specs means every design aspect of the .300 Blackout is kept similar, regardless of the manufacturer.

Ballistically, the .300 AAC Blackout has almost 17% more energy at 300 meters than the 7.62 x 39 round. This is because the latter is thicker and wider, causing more drag as a projectile. Compared with the muzzle energy of the .556, the .300 Blackout has the same muzzle energy that the .556 has at 500 meters while it is at 700 meters. This means the .300 Blackout is more effective at long distances.

The 220 grain subsonic .300 Blackout goes at about 1010 feet per second with 500 foot-pounds of muzzle energy. This makes the .300 Blackout an effective, versatile, and reliable close combat round. The .300 Blackout also comes in a supersonic variant, which means once fired, the bullet travels faster than the sound barrier. This high-speed feature means that the bullet will spend relatively less time in motion and thus less prone to the effects of elements like the wind.

The .300 Blackout is a worthy firearm since it gives you the ballistic power of an AK just by switching the upper in an AR. This compatibility means that it can allow for major savings if you're a gun enthusiast who likes to stay on a budget.

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, United Kingdom, and the United States, have adopted it. This is because most operators commend 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.

Barrel Lengths That Work for the AAC .300 Blackout

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 gun powder 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.

Having a longer or shorter barrel is a matter of understanding the dynamics of ammunition, barrel design, and overall shooting conditions before you settle on a preference. For instance, having a relatively long barrel has the gases from the already burned-out gunpowder trapped for longer, which means there will be more push time of the bullet by the gases. 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.

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.

From What Distance Will a .300 Blackout Kill a Deer?

The .300 Blackout is quite effective when hunting for animals like wild pigs, deer, or varmint. However, 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.

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 long-range targets. Plus, the long barrel compensates for its rather laborious maneuverability.

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.

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.

Contact our team at 80 Percent Arms to learn more.

.300 Blackout Guide: Best Barrel Length, Build Tips & More (2024)

FAQs

What barrel length is best for 300 Blackout? ›

A 16-inch barrel is the longest available barrel for the . 300 Blackout, and it is quite effective when it comes to long-range targets.

How far will a 300 Blackout shoot accurately? ›

In terms of hit probability, the Blackout has an effective range of 460 meters. From a 9 in (230 mm) barrel, the 125 gr BLK round has the same muzzle energy as the M855 from the M4, and 5 percent more energy at 440 meters.

How much does a 300 Blackout drop at 100 yards? ›

The bullet drops about 3 inches at 100 yards, 8 inches at 200 yards, 2 feet at 300 yards, 4.5 feet at 400 yards, and 9 feet at 500 yards. And how does that affect real-world accuracy?

What is the best twist for 300 Blackout? ›

A 1:7 or 1:8 twist rate works best with . 300 BLK. If you'll be shooting mostly supersonic loads with lighter projectiles (80 to 125 grains), opt for a barrel with a 1:7 twist rate. Because subsonic loads are made with heavier projectiles (usually 225 grains or more), you may be better served by a 1:8 twist rate.

What barrel length do special forces use? ›

Like standard M4s, the gun utilizes a 14.5-inch barrel, a flat-top upper receiver, collapsing stock, and railed handguard.

What is the fastest 300 Blackout bullet? ›

Barnes is the latest ammo maker to produce 300 BLK loads, and its new VOR-TX 110-grain TSX FB is our Ammo of the Year. It features a 110-grain, polymer-tipped, all-copper Triple Shock bullet that achieves 2,400 fps from a 16-inch barrel, producing 1,407 foot-pounds of energy. That puts it squarely in the .

Does barrel length affect accuracy 300 Blackout? ›

How Much Does Barrel Length Affect .300 Blackout Bullet Velocity?

Why does the military use 300 Blackout? ›

Why Special Forces Need 300 Blackout Subsonic Weapons

What is the advantage of 300 Blackout? ›

The . 300 BLK offers a wider range of projectile choices, thanks to the . 30 caliber bore, burns its full potential in a 9-inch barrel, and is a much better choice for hunting. It also has the ability to cycle both super and subsonic ammunition without modification.

What should I Zero a 300 Blackout at? ›

Zero considerations for 300 BLackout - YouTube

What grain bullet should I use in 300 Blackout? ›

Generally, the . 300 Blackout is loaded with 110- to 125-grain bullets for hunting. Velocities range from 2,200 to 2,350 fps, combined with the bullet weight and expansion characteristics delivering a very effective performance on game up to and including mule deer.

What grain is considered supersonic for 300 Blackout? ›

300 Blackout round (or 300BLK for short) can serve two roles. 300BLK has supersonic bullet speeds when loaded with lighter bullets in the 120 to 130 grain range.

Whats better 1/7 twist or 1/8 twist? ›

It is absolutely true that heavier, longer bullets in the 69-85 grain flavors like faster rifle twists of 1:8, or 1:7. When someone tells you, “if you want to shoot some operator level Mk262 77 grain OTM ammo, you need a 1:7 twist”, believe that they have your best interest at heart.

Do Special Forces use 300 Blackout? ›

300 Blackout ammunition and is designed for special operations forces. The . 300 Blackout, developed by U.S.-based Advanced Armament Corporation, uses a 5.56mm case cut down to accept the . 30-caliber bullet, so the larger round can be used with the bolt and magazine of M16s, M4s and other AR-style weapons.

Is there a difference between 300 Blackout and 300 AAC Blackout? ›

300 AAC Blackout : What's the Big Deal? - YouTube

Does a suppressor add to barrel length? ›

In summary, the length of a permanently attached muzzle device is added to both the barrel length and the OAL of a firearm for purposes of evaluating whether said firearm falls under the purview of the NFA.

Do you need a different lower for 300 Blackout? ›

You can use a standard 80 percent lower and mill it out when building a 300 Blackout without an issue. The difference between AR 15 Kits in 300 Blackout and 5.56 is essentially just the barrel. Barrels are not the easiest part to swap on a rifle, but a shooter can swap uppers in all of three seconds.

Is 300 BLK good for long range? ›

The 300 Blackout isn't for long range shooting. By long range I mean its no 6.5 Creedmoor, 308, or 224 Valkyrie. The 300 Blackout has a variety of effective ranges depending on the load you are using. Subsonic loads have less range than supersonic loads.

Will 300 Blackout penetrate body armor? ›

Is 300 BLK Effective After Penetration? We'll preface this with an obvious clarification: Any centerfire rifle shooting supersonic cartridges will cut through level IIIA soft body armor without much ado.

What is the effective range of a 300 Blackout subsonic? ›

Using M4 military standards, the max effective range of 300 AAC Blackout from a 16 inch barrel is 460 meters. From a 9 inch barrel (2050 fps): – 100 inches drop at 410 meters – 41 inches drift at 470 meters – 291 ft-lbs of energy at 625 meters, so 440 meter max effective range for a 9 inch.

Do Navy Seals use subsonic ammo? ›

Commandos have used subsonic bullets since World War II, though these are mainly effective in smaller guns like the .

Why is 300 Blackout better than 223? ›

However, the . 300 Blackout uses heavier and larger diameter bullets with more kinetic energy. For this reason, it's arguably a better cartridge for shots on big game inside 150 yards than the . 223 Remington (especially when used in a rifle with a good .

Does 300 Blackout have more recoil than 556? ›

Recoil — The . 300 BLK features recoil three times greater than the 5.56mm round, at 9 pounds. However, felt recoil is only slightly more, and has no impact on actual shooting. Range — The 5.56mm round features a variable range of about 500 yards, on average, compared to the 300 yards of the .

Which is better 6.5 Grendel or 300 Blackout? ›

The 6.5 Grendel is certainly the more powerful cartridge compared to the . 300 Blackout, even though it has a lighter bullet. However, it also has a significantly more powerful recoil than the .

What is the quietest 300 Blackout ammo? ›

Shooting 300 Blackout Ammo with a Suppressor

300 Blackout subsonic is one of the quietest rounds to suppress, particularly when fired through a closed breech firearm like a bolt action or single shot rifle. There is no noise from the action or any created via the ejection process as noticed in a semi automatic firearm.

How much does a 300 Blackout drop at 200 yards? ›

When hunting with a suppressor expect a 3-4 feet drop at 200 yards when using subsonic rounds and little energy from a 16" barrel. There is even less energy with a 10.5" barrel. Just keep in mind that 300 BLK, suppressed, was designed for close quarters.

What is the most accurate barrel twist? ›

The 1:8 twist barrel is the most versatile of the bunch. This twist rate gives you the most flexibility, effectively stabilizing projectiles up to 80 grains but not over stabilizing lighter ammunition. The 1:9 barrel is best for stabilizing lighter and mid-weight bullets ranging between 45 and 77 grains.

What grain bullet is best for 1 in 7 twist? ›

If you are shooting long range, or want more penetration, you want a heavier bullet in the AR, such as a 62- or (preferably) a 77-grain. While 62-grain bullets prefer a rate of twist around 1:8, 77-grain bullets weights favor a 1:7 twist rate.

What grain bullet is best for a 1 in 9 twist? ›

The 1:9 barrel is best for stabilizing lighter and mid-weight bullets between 45 and 77 grains.

How many rounds of ammo do Navy SEALs carry? ›

The basic combat load for Navy SEALs is 210 rounds of 5.56x45mm (0.21×1.77in) NATO. It's spread out between seven 30-round magazines (six carried and one loaded into the weapon).

What is a good 300 Blackout hunting round? ›

Best . 300 Blackout Ammo: Self Defense, Hunting, Target
RoleNameGrain
Best Plinking/TrainingMagtech First Defense123gn
Best Suppressed/SubsonicSellier & Bellot Subsonic200gn
Best SupersonicBarnes Vor-Tx110gn
Best Home DefenseFiocchi SST125gn

What is 300 Whisper ammo? ›

300 Whisper is a wildcat cartridge there were no established Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) specifications for the chamber reamers, and the necks were cut to allow for standard . 308 neck thickness, which is approximately the same thickness as produced from forming . 223 brass.

Can 300 BLK shoot 300 Whisper? ›

To keep things simple, think of it this way: You can shoot 300 Whisper in a 300 Blackout rifle. You should probably avoid shooting 300 Blackout in a 300 Whisper rifle because of the simple fact that the Whisper round is a wildcat cartridge.

Does barrel length affect accuracy 300 Blackout? ›

How Much Does Barrel Length Affect .300 Blackout Bullet Velocity?

Do you need a different lower for 300 Blackout? ›

You can use a standard 80 percent lower and mill it out when building a 300 Blackout without an issue. The difference between AR 15 Kits in 300 Blackout and 5.56 is essentially just the barrel. Barrels are not the easiest part to swap on a rifle, but a shooter can swap uppers in all of three seconds.

Is 300 BLK good for long range? ›

The 300 Blackout isn't for long range shooting. By long range I mean its no 6.5 Creedmoor, 308, or 224 Valkyrie. The 300 Blackout has a variety of effective ranges depending on the load you are using. Subsonic loads have less range than supersonic loads.

Why is Pistol length gas system 300 Blackout? ›

Since a subsonic 300 blackout round is heavy and uses less powder than supersonic rounds, it's crucial to utilize as much gas as possible to cycle the firearm.

Does a suppressor add to barrel length? ›

In summary, the length of a permanently attached muzzle device is added to both the barrel length and the OAL of a firearm for purposes of evaluating whether said firearm falls under the purview of the NFA.

What grain is subsonic for 300 Blackout? ›

Subsonic bullets generally boast a lighter recoil than their speedy relatives, and have an added weight coming to around 180-220 grains in a standard . 300 Blackout load. The additional bullet weight keeps the rounds from breaking the sound barrier, and gives them as much energy as possible.

Is there a difference between 300 Blackout and 300 AAC Blackout? ›

300 AAC Blackout : What's the Big Deal? - YouTube

Why is 300 Blackout so popular? ›

From its humble origins in the U.S. military, the 300 Blackout cartridge has swelled in popularity as more customers recognize its versatility and punch. One of the most difficult things retailers do is try to read the tea leaves when it comes to the next hot cartridge.

What kind of lower receiver do I need for a 300 Blackout? ›

Any standard AR15 lower works with the 300 blackout. The 300 BLK round was designed to work in the AR-15 platform.

Does a 300 Blackout need a heavy buffer? ›

If your rifle build is chambered in 300 Blackout, the carbine buffer weight should be used with subsonic ammo and a pistol-length gas system. This combination will achieve the best possible operation.

Does the military use the 300 Blackout? ›

300 Blackout is a formidable ammo choice and is used by both the military and law enforcement around the globe! Everyone knows that the king of intermediate cartridges is the 5.56x45mm NATO round. There is an enormous number of guns chambered to fit it, and all of the major manufacturers of ammunition love it.

Is mid length gas system better? ›

Since carbine- and mid-length gas systems measure similarly, bear in mind that you'll get better operation when the barrel length is closer to the middle of the functional range — a mid-length setup will better serve an 18-inch barrel than the carbine variety.

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