The United States Navy Mark 12 Mod 0/1 Special Purpose Rifle (SPR) is a rifle in service with United States Special Operations Forces in Operation Enduring Freedom and previously in Operation Iraqi Freedom. SPR initially stood for Special Purpose Receiver, but that nomenclature has been replaced as the weapon became a stand-alone weapons system, and not just an add-on upper receiver assembly (part of the proposed SOPMOD upgrades). The SPR was eventually type classified by the U.S. Navy as the Mk 12. Note that the weapon was developed by a Navy office (Naval Surface Warfare Center Crane Division) for SOCOM units, not for use by units that fall under the conventional US Navy.