180110-N-JE719-204 ATLANTIC OCEAN (Jan. 10, 2018) Machinist Mate (Weapons) 3rd Class Dennis J. Capello, left, guides Machinist Mate (Weapons) 3rd Class Derrick Bratten through a “clear and safe” check of a Mk 48 machine gun aboard the Pre-Commissioning Unit (PCU) Colorado (SSN 788). Colorado is the 15th Virginia-class attack submarine and is scheduled to be commissioned March 17, 2018. (U.S. Navy photo by Mass Communication Specialist 1st Class Jeffrey M. Richardson/Released)