Everything You Need to Know About 300 Blackout Ammo

Running 300 Blackout or thinking about it? 

This Q&A cuts through the internet fluff and provides you with straightforward answers on everything from ammo selection to barrel compatibility.

No guesswork, no BS. Just the information you need before making a purchase.

What is 300 Blackout?

300 Blackout, also known as 300 AAC Blackout or 300 BLK, is a rifle cartridge developed by Advanced Armament Corporation (AAC) in partnership with Remington Defense. It was officially introduced in 2011 to give AR-15 users the ability to shoot a larger, heavier bullet—especially in short-barreled and suppressed rifles—without needing to change their standard bolt or magazines.

The cartridge was based on the earlier 300 Whisper and was designed to solve a very specific problem: create a reliable round that delivers strong performance at close to medium ranges, functions well with a suppressor, and fits inside a standard AR-15 platform.

300 Blackout has become a favorite among civilian shooters, law enforcement, and military units because it balances power, accuracy, and versatility. It works great in both supersonic and subsonic configurations, making it ideal for hunting, home defense, tactical setups, or range time—especially when paired with a suppressor.

Will 300 blackout ammo chamber in a 223?

No—and trying it is extremely dangerous. While a 300 Blackout round might physically fit into a .223/5.56 magazine and may partially chamber in a .223/5.56 rifle, it should never be fired from one.

Here’s why: the .300 Blackout bullet is significantly larger in diameter than a .223/5.56 barrel is designed to handle. If a 300 BLK round is mistakenly chambered and fired in a .223 rifle, the bullet won’t fit down the bore. This creates catastrophic pressure buildup that can cause the rifle to rupture or explode—posing a serious risk of injury or death to the shooter and bystanders.

This kind of mix-up usually happens when both calibers are used at the range, since 300 Blackout and .223/5.56 share the same case dimensions at the base and can fit in the same magazines. That’s why it’s essential to clearly label your magazines and ammo boxes, and never mix 300 BLK and .223/5.56 ammo during a shooting session.

How much is 300 blackout ammo?

HOP Munitions, a veteran-owned company known for precision and innovation, offers several 300 Blackout options that punch above their price point in terms of quality and consistency:

What grain of 300 blackout ammo is good for hunting?

For hunting with 300 Blackout, subsonic 220 grain rounds like HOP Munitions’ 220gr Subsonic HPBT are a top choice—especially when using a suppressed rifle.

This load delivers controlled expansion and excellent weight retention, making it ideal for taking down deer or hogs at closer ranges. With a copper-plated jacket, lead-alloy core, and a boat tail design for better accuracy, it’s built for hunters who demand quiet precision and consistent terminal performance.

Will Ruger Mini 14 223 mags hold 300 blackout ammo?

Yes, Ruger Mini-14 .223 magazines can physically hold 300 Blackout rounds, since both cartridges share similar case dimensions.

However, using .223 mags for 300 Blackout isn’t recommended. The internal geometry isn’t optimized for the heavier 300 BLK bullets, which can lead to feeding issues and reliability problems. For best performance and safety, stick with magazines specifically designed for 300 Blackout.

Does 300 blackout ammo fit in a 5.56 magazine?

Yes, 300 Blackout ammo fits in standard 5.56 AR-15 magazines. It was designed to work with existing 5.56 mags without modification. Most shooters report reliable feeding, especially with quality mags like those from Magpul.

That said, feeding issues can still occur, particularly with subsonic rounds or certain bullet profiles. For the best performance—especially in suppressed setups—dedicated 300 Blackout magazines are recommended.

What ammo to use with a 300 blackout 1/8 twist barrel?

A 1/8 twist barrel in 300 Blackout offers excellent versatility. It works well with supersonic loads in the 110–150 grain range and also does a solid job stabilizing heavier subsonic rounds, like 190 to 220 grains.

If you’re running both suppressed and unsuppressed, a 1/8 twist gives you the flexibility to shoot just about any common 300 BLK load with reliable accuracy.

Is the 300 blackout ammo the same as 7.62×39?

No, 300 Blackout and 7.62×39 are not the same. While both are .30-caliber cartridges with similar ballistic performance, they have different case dimensions, bullet diameters, and chamber requirements. They are not interchangeable, and attempting to fire one in a rifle chambered for the other is unsafe and can cause damage.

Can I shoot .300 AAC Blackout ammo in a .223 Wylde barrel?

No—never attempt to fire .300 AAC Blackout ammo in a .223 Wylde barrel. While the cartridge may seem similar in size, the .300 BLK uses a larger-diameter bullet that will not safely travel through a .223/5.56 bore. Doing so can cause catastrophic failure to your firearm, including a blown-out receiver, destroyed magazine, and serious injury.

In a controlled test, firing 300 BLK in a .223 Wylde barrel resulted in a ruptured upper receiver, damaged bolt carrier group, and a destroyed barrel. The pressure buildup from trying to force a .30 caliber bullet through a .22 caliber bore is extremely dangerous.

Where to buy 300 blackout ammo?

If you’re looking for reliable, American-made 300 Blackout ammo, HOP Munitions is your go-to source. We offer a full lineup of supersonic, subsonic, and polymer-coated 300 BLK rounds, all manufactured with precision and consistency in mind. Whether you’re training, hunting, or running a suppressed setup, we’ve got the ammo you need—ready to ship.

👉 Shop 300 Blackout Ammo at HOPMunitions.com

What 300 blk ammo is used by special forces?

U.S. Special Operations units, including those within SOCOM, use 300 Blackout for specific mission sets that involve short-barreled, suppressed platforms. The round performs reliably in compact weapons like the SIG Sauer MCX Rattler, which has been fielded for close-in engagements where sound and flash suppression are critical.

Both subsonic and supersonic 300 BLK loads are used—subsonic for maximum suppression with minimal signature, and supersonic when more velocity and energy are required. These loads are typically tailored for barrier penetration and optimized terminal performance from shorter barrels. The ability to switch between sub and supersonic without changing platforms is a major reason why 300 Blackout has seen limited but specialized adoption among units like Delta Force and SEAL teams.

What is 300 blackout ammo good for?

300 Blackout ammo is best suited for suppressed shooting, short-barreled rifles, and close-range applications. It performs exceptionally well in AR-style pistols and SBRs, especially when paired with a suppressor.

Thanks to its ability to run both subsonic and supersonic loads, it’s a versatile choice for home defense, hunting, and tactical use. With more mass than 5.56 NATO, 300 BLK delivers greater energy on target while still maintaining controllable recoil. It’s most effective from 0 to 150 yards.

What is the best supersonic 300 blackout ammo?

One of the best options for supersonic 300 Blackout ammo is the HOP Munitions 147-grain FMJ. With a velocity of 1,950 feet per second and 1,240 ft/lbs of energy, it delivers consistent accuracy and reliable performance across a wide range of AR-platform rifles and pistols.

Whether you’re training at the range or running drills with your duty setup, HOP’s supersonic 300 BLK is built for shooters who demand precision, smooth cycling, and repeatable results—without breaking the bank.

What is the best 300 Blackout Ammo For Training and Practice?

For training and practice, HOP Munitions 220-grain 300 Blackout POLY is one of the best options available. These polymer-coated rounds are designed for safe, high-volume shooting—especially on steel targets.

They run reliably in both suppressed and unsuppressed rifles, regardless of barrel length or rate of fire. If you’re looking for clean, consistent, and affordable ammo that’s easy on your barrel and perfect for training sessions, HOP’s POLY rounds are the way to go.