Enhance the performance of your 9mm AR15 with the Ballistic Advantage 5.5" EPC (Enhanced Pistol Caliber) barrel.Precision-machined from 4150 CMV steel and finished with a QPQ corrosion-resistant treatment, this barrel ensures durability and reliability. The 1:10 twist rate optimizes bullet stabilization, while the 1/2x28 threads offer compatibility with a wide range of muzzle devices, including suppressors.Made in the USA, this barrel is a top choice for those seeking quality and performance in a compact package.Features Designed to work with both Colt/RR and Glock style AR builds. Compatible with standard mil-spec uppers. There are also numerous dedicated 9mm upper options that work. Requires the use of a unique magwell conversion (Colt/Rock River style) with UZI mags or a dedicated 9mm lower with Glock mags. 9mm on an AR15 platform operates by blowback and does not need a gas block or gas tube. Threaded 1/2x28 instead of 1/2x36 to give you greater versatility when choosing a suppressor. Integrated feed ramp and barrel extension. Since the "barrel extension" is an integral part of the barrel, the length stated is the true overall length. For example, an 11" 9mm barrel has the same outer dimensions/length as a 10.5" 5.56 barrel. Enhanced Feed RampIMPORTANT: A standard 1/2x28 flash hider will not have enough clearance for a 9mm round to pass. Before installing a muzzle device, ensure a 9mm round will drop freely through the muzzle device bore.