Product Description Build a dedicated .45 ACP AR upper with this Stern Defense Mod 5 M-LOK upper assembly featuring a 6-inch Black Melonite-finished barrel and an anodized, mil-spec flat-top upper receiver. The free-float M-LOK handguard is designed for excellent ergonomics while staying lightweight and strong, using a secure clamp-on mounting system intended to hold position under hard use and sustained firing. The assembly includes a mil-spec charging handle and a Stern bolt assembly engineered to run in Mil-Spec and Glock-pattern upper receivers and function with Colt SMG and Glock magazines, making it a strong foundation for a compact .45 ACP AR build. Product Highlights Free-float Mod 5 M-LOK handguard with secure clamp-on mounting for hard-use stability 6-inch .45 ACP barrel with durable Black Melonite finish for corrosion and wear resistance Mil-spec flat-top upper receiver with enlarged ejection port to accommodate larger rounds like .45 ACP Includes mil-spec charging handle for positive grip and one-hand manipulations Fully assembled bolt group with installed sub-components (firing pin, extractor, springs, and retaining pin) Specs Brand: Stern Defense Manufacturer Part Number: 015SD8INCHMOD5MLOK6INC UPC: 850001176576 Caliber: .45 ACP Barrel Length: 6 in Barrel Finish: Black Melonite Barrel Material: Chrome Moly Steel Handguard: Free-float M-LOK (6061 aircraft-grade aluminum, hard-coat anodized) with quick-disconnect swivel holes Upper Receiver: Mil-spec flat top (7075-T6 aluminum, hard-coat anodized) with laser-engraved dust cover and forward assist Receiver Features: Enlarged ejection port; dry film lube in bore Charging Handle: Mil-spec AR-15 charging handle (6061 aircraft-grade aluminum billet, hardcoat anodized) Bolt Material/Finish: 8620 AISI steel with Mag-Phosphate finish Compatibility Notes: Functions with Colt SMG and Glock magazines; compatible with standard AR15/M16 charging handles; bolt compatible with Law Tactical folding stock Weight: 3.405 lb Package Dimensions (L x W x H): 18.7 x 4.4 x 4.4 in Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the products manufacturer.