The Aero Precision EPC 9 Upper Receiver is the perfect start to your pistol caliber carbine. Accepting both 9mm & .40S&w Parts and components. This item features a last round bolt hold open, a feature built into the EPC upper receiver, allows the bolt to be locked open on an empty magazine.
Straight blowback system means this firearm does not need a gas block or gas tube. The EPC utilizes a direct blowback system, which directly uses the kinetic energy generated from the discharge of the cartridge, to push the bolt back and cycle the action.
Please Note: The larger bore diameter of the 9mm requires a 9mm specific muzzle device that allows proper clearance for the projectile. You will also need ensure the muzzle device is the appropriate thread pitch for your specific 9mm barrel (all Aero Precision 9mm barrels use 1/2×28 threads).