.300 Blackout (300 AAC Blackout, or 7.62×35mm) is the most versatile cartridge you can run in an AR-15. Developed in 2010 by Advanced Armament Corporation and Remington, it delivers true .30-caliber performance from a standard AR-15 — using your existing 5.56 magazines and bolt, with nothing more than a barrel swap. Run heavy subsonic loads suppressed for near-whisper-quiet shooting, or supersonic loads for hunting and defense out of short barrels where 5.56 falls short.
Below is the 300 Blackout ammo we keep in stock — subsonic loads around 190–220gr for suppressed use, and supersonic loads from 110–150gr for velocity, with single boxes and bulk options. Every order ships fast with secure checkout.
What Is .300 Blackout?
.300 Blackout fires a .308-diameter bullet from a case based on the 5.56 NATO, trimmed and necked up to .30 caliber. That design choice is the whole point: it runs in any standard AR-15 with just a barrel change — same lower, same bolt carrier group, same 5.56 magazines at full capacity. It was purpose-built to give the AR-15 platform real .30-caliber terminal performance from short, suppressed barrels.
Subsonic vs. Supersonic 300 Blackout
- Subsonic (≈1,000–1,050 fps): Heavy 190–220gr bullets that stay below the sound barrier. Paired with a suppressor, this is about as quiet as a centerfire rifle gets — ideal for suppressed range time, pest control, and stealthy hunting. The trade-off is a steep trajectory at distance.
- Supersonic (110–150gr, ≈2,000–2,400 fps): Flatter-shooting, harder-hitting loads for hunting and home defense. A supersonic 300 BLK out of a short barrel retains far more energy than 5.56 from the same length, which is why it's popular for SBRs and pistol-length AR builds.
300 Blackout Grain Weights Explained
| Grain weight | Velocity | Best for |
|---|---|---|
| 110–125gr | Supersonic | Hunting, defense, flat trajectory, max velocity |
| 147–150gr | Supersonic | Training, general-purpose plinking and range use |
| 190–208gr | Subsonic | Suppressed shooting, quiet range use |
| 220gr | Subsonic | Maximum suppression, suppressed hunting at close range |
What Is 300 Blackout Good For?
300 BLK shines for home defense and short-barrel builds, suppressed shooting, and hunting hogs and deer at moderate ranges (roughly inside 150–200 yards with the right load). Its biggest practical advantage is barrel length: it delivers full performance from 8–10" barrels, where 5.56 loses significant energy — making it ideal for compact, suppressed, maneuverable rifles and pistols.
300 Blackout Ammo FAQ
What's the difference between subsonic and supersonic 300 Blackout?
Subsonic 300 Blackout uses heavy 190–220gr bullets that travel below the speed of sound (about 1,000–1,050 fps), making it very quiet when suppressed. Supersonic 300 Blackout uses lighter 110–150gr bullets at higher velocity (around 2,000–2,400 fps) for a flatter trajectory and more energy at distance.
Can I shoot 300 Blackout in my 5.56 / .223 AR-15?
You need a dedicated 300 Blackout barrel, but everything else carries over — the same lower, bolt carrier group, and standard 5.56 magazines. Only swap the barrel or upper. Never load 300 BLK into a 5.56 chamber, as it can chamber and cause a dangerous overpressure event, so keep your ammo clearly separated.
What grain weight is best for 300 Blackout?
For suppressed, quiet shooting, choose subsonic 190–220gr. For hunting, home defense, or flatter-shooting supersonic use, choose 110–150gr. Match the load to your purpose and how your rifle's gas system is tuned.
Is 300 Blackout good for home defense?
Yes. Supersonic 300 Blackout delivers strong terminal performance from short barrels, which makes it popular for compact, suppressed home-defense AR builds where 5.56 loses energy.
How far is 300 Blackout effective?
Supersonic loads are effective for hunting roughly out to 150–200 yards depending on the load and bullet. Subsonic loads are best at closer ranges because the heavy, slow bullet drops quickly past about 100–150 yards.
Do you sell 300 Blackout ammo in bulk?
Yes. We offer bulk and multi-box options on select loads to lower your cost per round. Availability is shown on each product above.