The .300 Blackout is a rifle cartridge designed for short-range power and suppressor use

The .300 Blackout (also written as .300 BLK) is a rifle cartridge developed by Advanced Armament Corporation in 2011. It fires a .308-inch diameter bullet and was engineered to work in AR-15 rifles with minimal modifications — you swap the barrel and magazine, but the bolt carrier group and receiver stay the same. The cartridge was built specifically to perform well with a suppressor attached and to deliver reliable power at ranges under 300 yards.

The round sits between the standard 5.56 NATO cartridge (which is smaller and lighter) and larger rifle rounds like the 7.62×51 NATO. It uses a shorter case than most rifle cartridges, which is why it fits into an AR-15 platform without requiring a completely different gun. The .300 Blackout became popular with military units, law enforcement, and civilian shooters who wanted a suppressed rifle that was still effective in close-quarters situations.

Key Takeaways

  • The .300 Blackout fires a heavier bullet than 5.56 NATO and was designed to work well with sound suppressors attached to the barrel.
  • An AR-15 rifle can shoot .300 Blackout with only a barrel change; the receiver and bolt carrier group do not need to be replaced.
  • The cartridge is most effective under 300 yards and loses velocity faster than larger rifle rounds at longer distances.
  • Ammunition costs more than 5.56 NATO but is widely available from major manufacturers and online retailers.

How .300 Blackout compares to 5.56 NATO

The 5.56 NATO round is smaller and lighter than .300 Blackout. A 5.56 bullet typically weighs 55 to 77 grains, while .300 Blackout bullets range from 110 to 220 grains. Because .300 Blackout carries more weight, it delivers more energy at close range and penetrates barriers more reliably. The trade-off is that 5.56 NATO travels faster and flatter, making it better for longer-distance shooting.

In a suppressed rifle, the .300 Blackout has a real advantage. The 5.56 NATO round is supersonic (travels faster than the speed of sound), which means it creates a sonic crack even with a suppressor — the suppressor only reduces the muzzle blast. The .300 Blackout can be loaded as a subsonic round (slower than sound), and when paired with a suppressor, it becomes much quieter overall. This is why military and law enforcement units adopted it for operations where noise discipline matters.

Cost per round varies, but .300 Blackout ammunition typically runs 50 to 100 percent more than 5.56 NATO because it is produced in lower volume. Both are available from major manufacturers like Federal, Hornady, and Speer, and both are sold by online retailers and gun shops.

Subsonic vs. supersonic .300 Blackout loads

A subsonic load is ammunition where the bullet travels slower than 1,125 feet per second (the approximate speed of sound at sea level). Subsonic .300 Blackout rounds typically use heavier bullets — 190 to 220 grains — and slower-burning powder. When fired through a suppressor, subsonic ammunition is noticeably quieter because there is no sonic crack to suppress. The downside is reduced velocity and energy, which means shorter effective range and less penetration.

A supersonic load uses lighter bullets — 110 to 150 grains — and faster powder, pushing the bullet above the speed of sound. Supersonic .300 Blackout still benefits from a suppressor (the muzzle blast is reduced), but you will still hear the sonic crack. Supersonic loads retain more velocity downrange and hit harder, making them better for hunting or longer-range shooting within the cartridge's effective distance.

Shooters choose based on their purpose: subsonic for stealth and noise control, supersonic for power and range. Both types are sold by ammunition manufacturers, and the box will state the velocity so you know which type you are buying.

What rifles fire .300 Blackout

Any AR-15 rifle can be converted to .300 Blackout by swapping the barrel. The receiver, bolt carrier group, and trigger assembly remain unchanged. This makes the conversion inexpensive compared to buying a completely different rifle — a .300 Blackout barrel typically costs $100 to $300 depending on quality and features.

Several manufacturers also sell complete .300 Blackout AR-15 rifles ready to shoot. Brands like Daniel Defense, Sig Sauer, and Aero Precision offer factory-built models. Some bolt-action rifles and lever-action rifles have been chambered in .300 Blackout as well, though the AR-15 platform remains the most common.

If you already own an AR-15 in 5.56 NATO, you do not need to sell it or replace it. You can keep the 5.56 barrel and buy a .300 Blackout barrel separately, then swap between them depending on what you are shooting. This flexibility is one reason the cartridge became popular with shooters who wanted options without buying multiple guns.

Effective range and typical uses

The .300 Blackout is designed for ranges under 300 yards. At 100 yards, it delivers reliable power for hunting medium-sized game like deer and hogs. At 200 yards, velocity and energy drop noticeably, and beyond 300 yards, bullet drop becomes steep and energy falls significantly. This is by design — the cartridge was built for close-quarters military work, not long-range precision shooting.

Common uses include home defense (where range is typically very short), hunting in thick brush or timber (where shots are close), and suppressed shooting at ranges or training facilities. Law enforcement and military units use it for operations where noise control and close-range power matter more than long-distance capability. Civilian shooters often choose it for the same reasons: it works well with a suppressor, it hits hard at practical distances, and an AR-15 platform is familiar and modular.

Ammunition availability and cost

.300 Blackout ammunition is produced by major manufacturers including Federal, Hornady, Speer, and Remington. It is sold at gun shops, sporting goods retailers, and online ammunition dealers. Availability is generally consistent, though prices fluctuate based on demand and market conditions — there is no shortage of supply like there was during certain periods for other cartridges.

A box of 20 rounds typically costs $15 to $25 for standard factory loads, depending on bullet weight and whether the round is subsonic or supersonic. Bulk purchases (500 or 1,000 rounds) usually offer a per-round discount. Reloaders can also make their own .300 Blackout ammunition, which reduces cost if you already have reloading equipment, though this requires learning the process and investing in components and tools.

Frequently Asked Questions

Can I shoot .300 Blackout in a rifle chambered for 5.56 NATO?

No. The cartridges are different sizes, and forcing a .300 Blackout round into a 5.56 NATO chamber can damage the rifle or cause injury. You must use a rifle or barrel specifically chambered for .300 Blackout. If you own an AR-15, you can swap to a .300 Blackout barrel, but you cannot mix the two cartridges in the same barrel.

Do I need a suppressor to shoot .300 Blackout?

No. The cartridge works fine without a suppressor. A suppressor is optional and reduces noise, but it is not required for the round to function. Many shooters use .300 Blackout without a suppressor for hunting or target shooting.

Is .300 Blackout legal to hunt with?

Hunting regulations vary by state and by game animal. Most states allow .300 Blackout for deer and similar-sized game, but some states have minimum caliber or energy requirements that may exclude it for certain species. Check your state's hunting regulations before using it for hunting.

What is the difference between .300 Blackout and .300 Savage?

.300 Blackout and .300 Savage are different cartridges that are not interchangeable. .300 Savage is an older round designed for lever-action and bolt-action rifles, while .300 Blackout is modern and designed for the AR-15 platform. Using the wrong cartridge in the wrong rifle can cause serious damage.