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.300 Blackout Complete Upper Receivers

AR15Parts.com builds .300 Blackout complete upper receivers to order using barrels from Wilson Combat, Ballistic Advantage, and Satern. Every upper is assembled, headspaced, and function-checked in our shop. .300 AAC Blackout (7.62x35mm) was designed to deliver 7.62x39-class ballistics from a standard AR-15 platform using the same bolt carrier group and magazines you already own. The cartridge's real advantage is its ability to seamlessly switch between supersonic ammunition for range and terminal performance and subsonic ammunition for suppressed shooting — no parts changes, no adjustments. Whether you're building a suppressor-ready 300 Blackout pistol upper, a 16" hunting rig, or a do-everything home defense setup, configure your upper with your choice of barrel length, handguard, muzzle device, BCG, and charging handle.

Why Shooters Choose AR15Parts.com for .300 Blackout Uppers

Every .300 Blackout upper is assembled in-house, headspaced, and inspected before shipping. Our barrel options from Wilson Combat, Ballistic Advantage, and Satern deliver the accuracy and reliability this versatile cartridge demands. Each upper is built to your exact specifications. No FFL required — uppers ship directly to your door.

How to Choose the Right .300 Blackout Upper

Barrel Length & Gas System

.300 Blackout is one of few cartridges that performs well in short barrels. The cartridge achieves complete powder burn in as little as 9" of barrel, making 8" and 10.5" pistol uppers extremely effective — especially suppressed. A 16" barrel maximizes supersonic velocity for hunting and longer-range shooting. Short-barreled .300 Blackout uppers use a pistol-length gas system, while 16" barrels typically run carbine-length. Both are reliable and well-proven.

Complete Upper vs. Barreled Upper

Complete .300 Blackout uppers ship with BCG and charging handle installed. Barreled uppers come assembled without BCG or charging handle. Since .300 Blackout uses the same BCG as 5.56 NATO, many shooters already own a compatible bolt carrier.

Key Specifications

Muzzle Velocity: \~2,200 fps supersonic (125gr), \~1,050 fps subsonic (220gr) Effective Range: 300 yards supersonic, 200 yards subsonic Barrel Twist: 1:7 or 1:8 Recoil: Moderate, comparable to 7.62x39 Platform: Standard AR-15 lower receiver

.300 Blackout Upper Compatibility

One of .300 Blackout's biggest advantages is compatibility. The cartridge uses the same standard AR-15 BCG as 5.56 NATO. If you already own a 5.56 bolt carrier group, it works in your .300 Blackout upper. Standard AR-15 magazines also work, though we recommend .300 Blackout-specific magazines with modified feed lips for optimal reliability, especially with subsonic ammunition. The upper drops onto any mil-spec AR-15 lower with no modification. Suppressor compatibility is a major strength. The .300 Blackout was designed around suppressed use. With subsonic ammunition and a quality suppressor, it is one of the quietest centerfire AR platforms available.

Best Uses for .300 Blackout Uppers

Suppressed shooting is where .300 Blackout truly shines. With subsonic 220-grain loads through a suppressor, the report is hearing-safe — a capability no other mainstream AR-15 cartridge can match. This makes it the premier choice for home defense builds where hearing protection may not be available. Hunters use supersonic .300 Blackout loads for deer and hog hunting within 200 yards. The cartridge's heavy, large-diameter bullets deliver excellent terminal performance on medium game. Short-barreled .300 Blackout uppers are popular with hunters who need a compact, maneuverable platform for tight spaces and brush.

Frequently Asked Questions

What is included in a complete .300 Blackout upper?

Complete uppers include the upper receiver, barrel, gas block, gas tube, handguard, and muzzle device — assembled and headspaced. BCG and charging handle available as add-ons.

Can I use my 5.56 BCG in a .300 Blackout upper?

Yes. .300 Blackout uses the same standard AR-15 bolt carrier group as 5.56 NATO. Your existing 5.56 BCG is fully compatible.

Can I use regular AR-15 magazines with .300 Blackout?

Standard AR-15 magazines will work, but we recommend .300 Blackout-specific magazines with modified feed lips for the most reliable feeding, especially with subsonic ammunition.

Can a .300 Blackout upper fire suppressed?

Yes. .300 Blackout was designed specifically for suppressed use. With subsonic ammunition and a quality suppressor, it is hearing-safe and one of the quietest centerfire AR setups available.

What is the effective range of .300 Blackout?

With supersonic ammunition, .300 Blackout is effective to 300 yards. Subsonic ammunition is practical to 200 yards. For longer range needs, consider .223 Wylde or 6.5 Grendel.

Is .300 Blackout good for deer hunting?

Yes. With supersonic 110-150gr hunting loads, .300 Blackout is effective on whitetail deer within 200 yards. It is especially popular for hog hunting.

How long does shipping take?

Most in-stock configurations ship within 3-5 business days. Custom builds may take 2-3 weeks. Orders over $99 ship free.

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