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HSM's reputation for quality ammunition shows in this 300 Blackout subsonic offering. The 220-grain Sierra MatchKing bullet combined with careful loading creates a round that shoots clean and groups tight. Whether you're working with a suppressor or just want quiet range time, this load sits comfortably below the sound barrier at 1000 fps while delivering 489 ft-lbs of muzzle energy.
The Sierra MatchKing projectile is built for consistent, repeatable accuracy. With a thick copper jacket, boat tail design, and carefully shaped ogive, these bullets minimize drag and deliver tight groups shot after shot. The hollow point design supports reliable feeding while maintaining the precision these bullets are known for. This is match-grade ammunition that performs like it.
With velocity carefully controlled at 1000 fps, this load stays subsonic across a wide range of barrels. When paired with a suppressor, it produces minimal sound signature, making it a favorite for tactical training, precision practice, and situations where noise matters. The 220-grain projectile weight provides stable flight even at subsonic velocities, though it will fly like a brick at close range rather than following the arc of supersonic loads.
Brass casings are reloadable, and HSM loads each round using quality components and careful process control. The result is ammunition that feeds reliably and performs consistently from round to round. This consistency across a 20-round box is what you're paying for with match-grade ammunition.
Subsonic loads produce lower pressure, which can make reliable cycling challenging in some gas-operated rifles. A suppressor adds back pressure and helps achieve full function. If you're running it without a suppressor, check that your rifle has an H2 or heavier buffer and consider an adjustable gas block. Bolt-action rifles cycle fine either way.
Sierra MatchKing bullets are designed for precision target work, not hunting. They have thin jackets optimized for accuracy rather than expansion. For hunting applications, you'll want purpose-built expanding bullets that are designed for reliable terminal performance on game.
This subsonic load runs at 1000 fps with the heavy 220-grain bullet. Supersonic 300 Blackout typically uses lighter bullets (110-150 grains) and runs around 2000 fps, offering flatter trajectory and more energy downrange. Subsonic excels at noise reduction with a suppressor and works great for precision shooting at shorter distances, while supersonic trades quiet for reach and stopping power.
Yes. HSM uses quality brass with Boxer primers that are fully reloadable. After firing, you can resize, reload, and shoot again. That said, follow proper reloading procedures and work up loads carefully, especially with subsonic applications where pressure management matters.
| Caliber/Gauge | .300 AAC Blackout |
|---|---|
| Case Material | Brass |
| Cost per Round | 1.80 |
| Grains | 220 gr |
| Length | 6.1500 |
| Manufacturer | |
| Manufacturer Part Number | 300BLK4N |
| Units per Box | 20 |
| UPC | 837306006784 |
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