A barrel mounting and retention device for attaching a barrel to a receiver of a firearm. The barrel mounting and retention device can include a barrel extension disposed at a proximal end of the barrel, with an annular collar extending from the barrel extension and defining a first clamp face. A mounting plate having a second clamp face and defining a first axial bore fits over the barrel of the firearm with the barrel extending through the first axial bore. At least a portion of the second clamp face abuts a portion of the first clamp face as the mounting plate is secured to the barrel extension for mounting and retaining the barrel in communication with the receiver of the firearm.