Stern Defense Barrel Features The Stern Defense Barrel is cut from chrome moly steel a material chosen for its strength and resistance to the stress of repeated firing in a pistol caliber AR build. Its 1:16 twist rate is matched specifically to .45 ACP giving the bullet the right amount of spin for stable flight and consistent accuracy downrange. At 10.5 inches the barrel strikes a balance between a compact overall package and the barrel length needed for reliable cycling in a .45 ACP platform. This combination makes it a strong foundation for a dedicated 45 caliber AR upper build. Finished in Black Melonite the barrel gains an extra layer of corrosion and wear resistance that helps it hold up over a long service life. The .578x28 threaded muzzle lets the builder add a compensator flash hider or suppressor without needing an adapter opening up a range of configuration options. Because it is sold as a standalone barrel it drops directly into a builder s own .45 ACP upper receiver project. This barrel gives anyone assembling a 45 ACP AR platform a dependable corrosion resistant foundation to build around. Stern Defense Barrel Specifications Manufacturer: Stern Defense Model: Barrel Caliber: .45 ACP Material: Chrome Moly Steel Finish: Black Melonite Twist Rate: 1:16 Barrel Length: 10.5 Thread Pattern: .578x28 Available At: GrabAGun