Stern .45 ACP barrels are the perfect choice for firearm enthusiasts looking to build a custom, dedicated .45 ACP AR-15 upper group. Precision-machined to exacting tolerances, these barrels are crafted with an uncompromising commitment to quality and performance. Designed for reliability and accuracy, they provide a solid foundation for a high-performing AR-15 build. Whether for competition, tactical applications or recreational shooting, the SD .45 ACP barrel delivers the durability and precision needed to elevate any shooting experience. Barrel length is measured in overall length from breech to muzzle, providing clarity for users when selecting or fitting barrels to their firearm This barrel is threaded 0.578-28 4150 chrome-moly steel, known for its toughness and resistance to wear and tear, ensuring long lasting performance 1:16 inches twist, suitable for lighter, smaller projectiles, enhancing accuracy and efficiency Melonite coating, enhancing the surface hardness and corrosion-resistance of metal components Barrel comes with locating pin installed, simplifying installation and ensuring precise alignment for consistent performance