PRO2A LEFT HAND 5" 5.56 NATO 1/5 Micro Length Melonite M-LOK AR-15 Upper with Flash Can

Ultra-Compact Power with True Left-Side Ejection

Experience the ultimate footprint optimization without compromising on southpaw ergonomics. The PRO2A Left Hand 5" 5.56 NATO Micro Upper Receiver Assembly is explicitly engineered to eliminate blowback gas and spent casings from crossing a left-handed shooter's line of sight. Featuring an ultra-short 5-inch barrel paired with a fast 1:5 twist rate, this micro upper ensures proper stabilization of projectiles out of short-profile gas setups. Equipped with a pre-installed slimline tactical flash can, it directs concussive blast and muzzle flash straight downrange away from the operator. Drops natively onto any standard left-handed or ambidextrous AR-15 lower receiver platform. Proudly 100% designed, machined, and precision-assembled in the USA.

Key Features

Mirrored Left-Hand Ejection Port: Engineered with a dedicated left-eject mechanism that safely isolates hot brass and excess gas blast away from left-handed shooters' eyes and faces.
Ultra-Fast 1:5 Twist Rate: Crucial for micro-length 5.56 setups, the aggressive 1:5 twist rate provides rapid rotational torque to properly stabilize standard-weight projectiles over a brief 5-inch rifling path, maintaining mechanical consistency.
Melonite/Nitride Surface Treatment: The premium 4150 CMV steel barrel is fully Nitride/Melonite treated inside and out. This hard-surface treatment maximizes barrel longevity, counters aggressive micro-gas wear, and delivers excellent corrosion resistance.
Integrated Slimline Flash Can: Pre-installed on the muzzle to handle the intense blast pressures typical of micro-barreled 5.56 setups. It acts as a linear director, projecting noise, concussive pressure, and flash straight toward the target.
Free-Float Modular M-LOK Rail: Constructed from rigid 6061-T6 aluminum, the slimline handguard isolates barrel vibrations for uniform accuracy while offering M-LOK mounting locations and an upper Picatinny rail.

Technical Specifications

Receiver	Dedicated Left Hand (Left Eject), Billet Aluminum, M4 Feed Ramps, Type III Hardcoat Anodized Black
Barrel Length & Profile	5 Inch Medium Profile, 4150 Chrome Moly Vanadium Steel
Caliber	5.56 NATO (Backward compatible with .223 Remington)
Twist Rate	1:5 Twist (Optimized for short-barrel stabilization)
Gas Operating System	Micro-Length System, Low-Profile Gas Block Machined from 4140 Steel, Stainless Steel Gas Tube
Muzzle Device	Standard 1/2-28 Thread Pitch, Pre-Installed Slimline Tactical Flash Can (Directs blast forward)
Handguard	6.5 inch Competition Top Free-Float M-LOK Rail, Slim Profile, Machined from 6061-T6 Aluminum
Manufacturing Origin	100% Made in the USA with Pro2A Tactical Lifetime Factory Warranty

Who Chooses This Upper Receiver?

Southpaw PDW & Truck Gun Builders

Left-handed operators looking to build an ultra-compact Personal Defense Weapon (PDW) choose this mirrored upper to achieve maximum portability in vehicles or tight quarters without having hot casings or unburnt powder redirected into their face.

Left-Handed AR Pistol Enthusiasts

Shooters wanting a highly compact, fun, and fast-handling AR pistol setup select this configuration for its fast 1:5 twist rate, which fixes the key stabilization issues found on standard short-barrel builds.

Tactical Indoor Trainers

Left-handed shooters training inside confined environments select this flash-can-equipped upper. It channels the aggressive acoustic concussion of the 5" micro barrel completely forward and away from the shooter and adjacent lane operators.