7.5 inch 4150 Chrome Moly Vanadium barrel in 5.56 NATO with 1:7 twist rate, contour profile, manganese phosphate finish, pistol length gas system, micro low profile gas block, Black Diamond Series slick side billet upper receiver made from 6061-T6 aluminum with Type III hard coat anodized finish, 7 inch freefloat M-LOK Super Light Series handguard, and GI birdcage flash hider. This pistol upper build kit delivers ultra-compact AR-15 performance with a distinctive slick side profile.
The 7.5 inch barrel length creates an ultra-compact package with significantly reduced overall length compared to standard carbine configurations. The 1:7 twist rate stabilizes heavier 5.56 NATO bullets in the 62 to 77 grain range, though velocities will be substantially reduced compared to longer barrels. The contour profile tapers from chamber to muzzle, balancing weight distribution while maintaining structural integrity. The manganese phosphate finish protects against corrosion and provides a durable non-reflective surface. The pistol length gas system uses the shortest standard gas tube length, positioning the gas port closer to the chamber to ensure adequate gas pressure for reliable cycling with the limited barrel length. The .750 gas block journal provides compatibility with adjustable gas blocks if you want to fine tune gas flow for suppressed use. Expect significant muzzle flash and concussion with this barrel length, particularly with standard ammunition.
The Black Diamond Series billet upper receiver is machined from a solid block of 6061-T6 aluminum and features a slick side design without a forward assist. The absence of the forward assist creates a streamlined profile, reduces weight, and simplifies the upper receiver design. The slick side look appeals to builders who prefer a cleaner aesthetic or who consider the forward assist unnecessary for their intended use. The billet construction allows for precise tolerances and distinctive styling compared to standard forged uppers. The Type III hard coat anodized finish provides superior wear resistance compared to standard Type II anodizing, creating a harder surface that better resists scratches and abrasion from extended use.
The 7 inch freefloat M-LOK Super Light Series handguard extends nearly to the muzzle device on the 7.5 inch barrel, maximizing accessory mounting space while maintaining the compact profile. The Super Light Series design prioritizes weight reduction through optimized material distribution and slimmer wall sections compared to standard handguards. The M-LOK slots on the sides and bottom allow direct attachment of lights, grips, and other accessories using M-LOK compatible mounts without the weight penalty of full length Picatinny rails. The freefloat design means the handguard does not contact the barrel, eliminating pressure points that can shift point of impact as the barrel heats. The lightweight construction helps balance the overall weight distribution on this compact pistol upper.
Follow safe handling and manufacturer instructions. Ensure compliance with all applicable laws. BCG and charging handle are not included.
Caliber: 5.56x45mm NATO
Barrel: Bear Creek Arsenal "Irithyll" AR-15 AR Pistol Barrel
Barrel Length: 7.5 inches
Barrel Material: 4150 Chrome Moly Vanadium
Barrel Twist Rate: 1:7
Barrel Finish: Manganese Phosphate
Barrel Profile: Contour
Barrel Gas System Length: Pistol
Barrel Thread Pitch: 1/2x28
Gas Block: Micro Low-Profile Gas Block
Gas Block Size: 0.750 O.D
Muzzle Device: AR-15 1/2x28 TPI GI Birdcage Flash Hider
Muzzle Thread Pitch: 1/2x28
Upper Receiver: Black Diamond Series AR-15 Slick Side Billet Upper Receiver
Upper Receiver Material: 6061-T6 Billet Aluminum
Upper Receiver Finish: Type III Hard Coat Anodized
Handguard Style: Free Float M-Lok Super Light Series
Handguard Length: 7 inches
Handguard Color: Black
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