The 300 Blackout 125gr Sierra pairs the 300 Blackout cartridge with a 125gr Sierra MatchKing projectile in a dependable supersonic load. Genuine, in-stock and ready to ship, this 300 Blackout 125gr Sierra is built to deliver consistent, reliable results from your rifle every time you pull the trigger.
Specifications
| Caliber | 300 Blackout |
| Bullet weight | 125gr |
| Projectile | Sierra MatchKing |
| Type | Supersonic |
| Case | Factory-new brass |
| Quantity | 20-round box |
The Sierra MatchKing bullet
At the heart of this 300 Blackout 125gr Sierra is the Sierra MatchKing, chosen to match the supersonic role this load is built for. It is loaded on factory-new brass to consistent tolerances, the foundation of both reliability and accuracy.
That round-to-round consistency is what lets the load shoot to the same point of impact shot after shot — exactly what you want whether you are hunting, training or competing.
Supersonic performance and reach
This 300 Blackout 125gr Sierra runs supersonic for a flatter trajectory and more retained energy downrange, extending your practical range. You trade the whisper-quiet subsonic signature for velocity and on-target authority.
It is a strong choice when reach, speed and energy matter more than maximum quiet, and it performs from the short barrels the cartridge was built around.
What it is best for
This 300 Blackout 125gr Sierra suits hunting, defense and general-purpose shooting at supersonic ranges. Match the load to your task, confirm your zero before you rely on it, and it rewards you with dependable performance.
Different loads print to different points of impact, so always verify your zero with this specific round. For help choosing, read our 300 Blackout subsonic vs supersonic guide.
Why buy from Blackout Ammunition
We stock genuine, in-stock 300 Blackout ammunition and ship fast to lawful destinations nationwide. Every order is handled by people who know the cartridge, so if you are unsure which load fits your build, just ask. Browse the full 300 Blackout lineup, review our shipping & delivery details and the FAQ, and find suppressors and components at our sister store, blackoutammo.shop.
About the 300 Blackout cartridge
300 Blackout is one of the most versatile cartridges for the AR-15, delivering .30-caliber performance from a short, suppressor-friendly barrel using standard magazines. It runs equally well as a quiet subsonic load or a hard-hitting supersonic round simply by changing ammunition.
That flexibility is the cartridge’s signature strength, and it is exactly why so many shooters build around it. This 300 Blackout 125gr Sierra fits naturally into a 300 Blackout setup for hunting, defense or suppressed shooting.
Storage and getting the most from it
Like all quality ammunition, this 300 Blackout 125gr Sierra keeps for years when stored cool, dry and stable, away from heat and humidity. Before you rely on it, put a few rounds downrange to confirm your zero and grouping in your specific rifle.
A little range time up front turns this load into one you can trust completely when it matters most.
Fast shipping and ordering
We ship most in-stock orders quickly and securely to lawful destinations across the United States, with tracking so you know where your order is. Ordering the 300 Blackout 125gr Sierra is straightforward, and our team is available if you need help before or after your purchase.
Review our shipping and delivery details for timelines and any state or item-specific requirements before you order.
Genuine products, real support
When you buy the 300 Blackout 125gr Sierra from Blackout Ammunition, you get a genuine product handled by people who actually know the platform — not a faceless warehouse. We stand behind what we sell and are here to help you build and shoot with confidence.
Have a question first? Our FAQ covers the common ones, and you can always reach out for personal guidance.
Frequently asked questions
Is this 300 Blackout 125gr Sierra subsonic or supersonic?
It is a supersonic load — flatter-shooting with more reach.
What rifle does this 300 Blackout 125gr Sierra work in?
Any properly chambered 300 Blackout rifle.
Can I shoot it suppressed?
Yes, though as a supersonic load it still produces a sonic crack.
How many rounds per box?
20 rounds per box.
Is it genuine, in-stock ammunition?
Yes — genuine and ready to ship to lawful destinations.
You must be 21 or older to purchase rifle ammunition. All ammunition ships via ground to lawful destinations only; it is the buyer’s responsibility to comply with all federal, state and local laws.
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