Mk 12 Special Purpose Rifle

The United States Navy Mk 12 MOD 0/1/H Special Purpose Rifle (SPR) is a designated marksman rifle that was in service with United States special operations forces in the designated marksman role until 2017, also designed to be shorter than standard weapons. SPR initially stood for Special Purpose Receiver as it referred to an add-on upper receiver assembly (part of the proposed SOPMOD upgrades), but that nomenclature changed to Special Purpose Rifle as the weapon became a stand-alone weapons system.
The SPR was eventually type-classified by the U.S. Navy as the Mk 12. The weapon was developed by the Naval Surface Warfare Center Crane Division for US military special operations units.
The rifle is designed to fire semi-automatically, although it has the option to fire in full auto in case of emergencies.