The Moriarti Micro ARP 300 Blackout Upper Assembly is designed for shooters looking for a compact, versatile, and performance-driven AR-15 configuration. Featuring a 5-inch .300 AAC Blackout barrel, micro-length gas system, slim M-LOK free-float handguard, and suppressor-ready threaded muzzle, this upper provides an ideal foundation for a lightweight AR-15 build.

The Micro 300 Blackout Upper takes advantage of the short-barrel performance characteristics of the .300 AAC Blackout cartridge while maintaining compatibility with standard AR-15 lower receivers and common AR-15 components.

Built with a durable 7075-T6 forged aluminum A3 flat-top upper receiver, nitride-treated 4150 CMV barrel, and quality components, this upper delivers reliable performance for recreational shooting, custom builds, and compact AR configurations.

Key Features

Caliber: .300 AAC Blackout
Platform: AR-15
Configuration: Pistol Upper Assembly
Barrel Length: 5"
Barrel Material: 4150 Chrome Moly Vanadium (CMV)
Barrel Finish: Black Nitride
Twist Rate: 1:7
Gas System: Micro Length Gas System
Gas Block Diameter: .750
Muzzle Thread: 5/8x24 TPI
Muzzle Device: A2 Flash Hider
Handguard: 4" Slim M-LOK Free-Float Rail
Upper Receiver: A3 Flat Top 7075-T6 Forged Aluminum Upper Receiver
Finish: Black Hardcoat Anodized
Forward Assist: Installed
Dust Cover: Installed
BCG: Not Included
Charging Handle: Not Included
Manufacturing: Made in USA

Features

5" .300 AAC Blackout Barrel

The 5-inch 4150 Chrome Moly Vanadium barrel provides a compact and durable platform designed around the strengths of the .300 AAC Blackout cartridge.

Features include:

• 4150 CMV steel construction
• Black nitride finish for corrosion resistance
• 1:7 twist rate for stabilizing a wide range of projectile weights
• Optimized for compact AR-15 configurations

The .300 AAC Blackout cartridge provides flexibility with both subsonic and supersonic ammunition, making it one of the most versatile calibers for short-barrel AR platforms.

Micro Length Gas System

The micro-length gas system is designed specifically for compact barrel configurations, helping provide reliable cycling while maintaining the lightweight profile expected from a short AR-15 upper.

Suppressor Ready 300 Blackout Configuration

The 5/8x24 threaded muzzle allows compatibility with a wide range of muzzle devices and suppressor configurations where legally permitted.

The .300 AAC Blackout cartridge is especially popular among suppressed shooters because it supports both subsonic and supersonic ammunition options.

Slim M-LOK Free-Float Handguard

The 4-inch slim M-LOK free-float handguard provides accessory mounting capability while maintaining a compact overall profile.

Features include:

• Free-float design
• M-LOK accessory compatibility
• Lightweight construction
• Compact AR pistol configuration

Forged 7075-T6 AR-15 Upper Receiver

The A3 flat-top upper receiver is manufactured from 7075-T6 forged aluminum and hardcoat anodized for durability and long-term reliability.

Features include:

• 7075-T6 forged aluminum construction
• A3 flat-top Picatinny rail
• Black hardcoat anodized finish
• Forward assist installed
• Dust cover installed
• Compatible with standard AR-15 lower receivers

Perfect For

The Moriarti Micro 300 Blackout Upper is ideal for:

• Compact AR-15 pistol builds
• 300 BLK conversions
• Short-barrel AR configurations
• Suppressor-ready builds
• Lightweight AR projects
• Range shooting
• Recreational shooting
• Custom AR-15 builds

Will this Micro 300 Blackout Upper fit my AR-15 lower?

Yes. This upper assembly is designed to fit most standard mil-spec AR-15 lower receivers.

Does this upper include a bolt carrier group?

No. The bolt carrier group is not included. This upper is designed to work with a standard AR-15/M16 pattern bolt carrier group.

Is the charging handle included?

No. The charging handle is not included and can be purchased separately.

Can I use subsonic and supersonic 300 Blackout ammunition?

Yes. The .300 AAC Blackout cartridge was designed to function with both subsonic and supersonic ammunition. Performance depends on ammunition selection and the overall firearm configuration.

Is this Micro 300 Blackout Upper suppressor compatible?

Yes. The 5/8x24 threaded muzzle accepts compatible muzzle devices and suppressors where legally permitted.

Why choose a Micro 300 Blackout Upper?

A Micro 300 Blackout Upper provides a compact AR-15 configuration while maximizing the advantages of the .300 AAC Blackout cartridge in a short-barrel platform. It is a popular choice for shooters who want a lightweight, maneuverable, and versatile AR build.

Related Products

300 Blackout Uppers

300 Blackout Pistols

300 Blackout Build Kits

AR-15 Lower Receivers

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