PRO2A 16" 450 Bushmaster 1/24 Carbine Length Melonite M-LOK AR-15 Upper Receiver

Bring devastating, big-bore thumper performance to your standard AR-15 platform with this premium 100% American-made upper receiver assembly. The PRO2A 16" 450 Bushmaster Carbine Length Upper anchors a match-ready, premium Melonite-treated 4150 CMV barrel to a mil-spec forged upper receiver specifically modified for heavy large-diameter case ejections. Complete with a specialized big-bore Nitride bolt carrier group, an ultra-slim 15-inch free-float M-LOK handguard, and an optimized gas operating system, this assembly delivers everything required to seamlessly convert your existing lower configuration into a hard-hitting legal straight-wall hunting rifle or maximum-energy tactical asset.

Key Features

Option For Specialized Big-Bore Nitride Bolt Carrier Group: Engineered precisely out of premium steel with a slick nitride finish. Featuring a widened, caliber-matched bolt face depth and a heavy-duty extractor assembly, it ensures uniform heavy case extraction and rock-solid reliability across commercial hunting profiles.
Heavy-Duty Melonite Barrel Protection: The 16-inch 4150 CMV steel barrel is fully treated with an advanced Salt Bath Melonite finish inside and out. This premium chemical hardening vastly extends bore life against rapid gas throat erosion at the port and shields components against harsh moisture in the field.
Precision 1:24 Right-Hand Twist: Precision button-rifled with a 1:24 twist configuration explicitly tailored to stabilize large-diameter, straight-wall 450 Bushmaster projectiles ranging from 250gr to 300gr, delivering tight grouping profiles and uniform downrange velocity.
Modified Large-Ejection Port: The forged upper receiver features an opened and smoothed ejection port profile designed intentionally to support the clean clearing path of spent thick brass, preventing traditional stovepipe cycling jams.
Slim Profile Free-Float M-LOK Rail: Crafted from premium 6061-T6 aluminum, the free-float rail isolates barrel vibrations to preserve uniform mechanical accuracy while providing massive M-LOK modular real estate.

Technical Specifications

Upper Receiver	Big-Bore Milspec Upper Receiver, Forged 7075-T6 Aluminum, Widened and Optimized Ejection Port, Single Large Feed Ramp, Type III Hardcoat Anodized Black - Forward Assist & Port Cover
Barrel Length & Steel	16 Inch Profile, 4150 Chrome Moly Vanadium (CMV) Steel, Heavy Contour, Melonite Treated
Caliber	450 Bushmaster (Legal for straight-wall state hunting mandates)
Twist Rate	1:24 Twist (Optimized to stabilize heavy intermediate big-bore projectiles from 250 grain to 300 grain)
Gas Operating Block	Carbine-Length Direct Impingement System, Low-Profile 0.750" Gas Block Machined from 4140 Steel, Stainless Steel Gas Tube
Muzzle Device	5/8-24 Thread Pitch - Enlarged to 45 Cal , A2 Flash Hider with Crush Washer Pre-Installed
Handguard	12 Inch Slim Profile Free-Float M-LOK Rail, Full-Length Top Picatinny Rail, Machined from 6061-T6 Aluminum
Manufacturing Origin	100% Made in the USA with Pro2A Tactical Lifetime Factory Warranty

Why Choose This Product?

The PRO2A 16" 450 Bushmaster Carbine Length Melonite M-LOK Upper directly solves the three biggest hurdles facing big-bore AR-15 builders: structural casing clearing jams, severe throat erosion from heavy powder charges, and erratic part-by-part home build tolerances. While standard rifle upper geometries often choke on wide straight-wall casings, Pro2A Tactical builds this system around a custom-widened ejection port profile paired with a matched Nitride big-bore bolt carrier group. This configuration ensures smooth, unhindered case ejection and rapid cycling out of the box with your preferred hunting ammunition.

Opting for a 16-inch medium contour barrel path offers a massive physical advantage for whitetail and large-game hunters working under strict straight-wall state restrictions. It delivers a highly compact, agile rifle footprint that maneuvers around deer stands and dense brush effortlessly, while granting the fast-burning 450 Bushmaster cartridge the perfect bore length to realize its optimal velocity metrics and bone-crushing kinetic energy. Backed completely by Pro2A Tactical's signature Lifetime Factory Warranty and engineered with 100% American craftsmanship, this premium upper converts your standard lower receiver into a premier, duty-ready thumper platform with absolute confidence.