evolution, certain conditions must exist prior to firing. Making sure that the gun is pointed in a safe direction, that all the loading equipment is in the fire position (out of the way of recoiling parts), and that the breechblock is all the way closed are just a few of the obvious things that must be correct before firing. A typical electronic firing  circuit  includes  inputs  that  monitor  these  and many other conditions, allowing firing voltage to pass only  after  all  safety  conditions  have  been  satisfied. Firing  Cutouts A firing cutout mechanism interrupts firing when the gun is pointed at or near the ship's permanent structure. A firing cutout is a mechanical device that monitors  gun  position. The  components  we  have  just  described  are common to all guns. We will now discuss the individual gun  systems  in  the  fleet  today,  paying  particular attention to the loading system in each one. GUN SYSTEMS LEARNING OBJECTIVES: List and explain the different gun mounts used aboard ship. Explain crew position and responsibilities and loading  sequence  when  operating  gun  mounts. As you read this section and study the illustrations, note  the  different  configurations  of  machinery  designed to accomplish the same task from one gun to the next. When we are speaking of gun equipment, all directional nomenclature (left, right, front, back) is relative to the muzzle of the gun (the end of the barrel from which the projectile exits when fired); the muzzle is to the front as you stand inside the gunhouse. 5"/54 MK 42 GUN In the 1950s as potential targets became faster and more sophisticated, a gun with more range and a faster rate of fire was needed. The 5"/54 Mk 42 was developed to effectively engage these targets as well as shore targets. Several versions of the Mk 42 gun have seen service since then. In the fleet today, you will find only the Mod 9 and the Mod 10; all others have been retired. The two versions are identical in many respects. The differences will be pointed out at the end of this section. The 5"/54 Mk 42 is an automatic, dual-purpose gun mount. It can be controlled either remotely from a fire control system, usually the Mk 68 GFCS, or locally from the mount at the One Man Control (OMC) station. The normal mode of operation is the remote mode. The mount fires an average 70-pound projectile up to 26,000 yards with a 48,000-foot ceiling. The gun, with its automatic loading system, has a rate of fire of 34 rounds per  minute. As you will see, the loading system is actually two almost separate systems, left and right. The ammunition carrier and the hydraulic power drive units are the only components shared by both sides. The advantage of having separate systems is readily apparent. In the event of a casualty, you can isolate the affected side and continue to fire at 17 rounds per minute from the other side. We will now describe the major components of the mount as we walk through a loading cycle. Figure 6-15 illustrates the major components of the 5"/54 Mk 42 gun. The gun is operated by the mount captain from the EP2 panel. Electrical power is supplied to the gun through the EP1 panel. Both the EP1 and EP2 panels are located in the compartment directly under the mount,  along  with  the  lower  hoist  power  drive, ammunition carrier, and upper hoists. This compartment is commonly called the carrier room. Inside the gun mount, there are two manned positions: the gun captain and  the  OMC  operator.  The  gun  captain  has  the responsibility of monitoring the operation of the gun and relaying bore reports (whether or not the gun bore is clear) after each round or salvo is fired. The OMC operator  functions  as  a  check  sight  observer  during normal  firing.  As  check  sight  observer,  he  uses  the telescopic sight to ensure that the gun is trained on the intended target. He then reports CHECK SIGHT ON TARGET. The loader drums, located in the projectile magazine, are served by the magazine crew. The magazine crew is made up of Seamen from various divisions of the ship. You may be assigned to this station. Here,   you   will   remove   propelling   charges   and projectiles from their storage bins and load them into the loader drums at the command of the mount captain. Some individuals from the magazine crew also serve as members   of   the   hot   gun   clearing   team.   The responsibilities of this team will be described later in this  chapter. When a remote order is received, the mount captain gives control of gun train, elevation, and firing circuit to the fire control system. When ordered to fire, the mount captain initiates the loading cycle by pressing the RAM ONCE or the RAM CONTINUOUS button on the EP2 panel. RAM ONCE allows one round to be loaded  and  fired.  RAM  CONTINUOUS  allows  the  gun to continue firing until it is empty or ordered to stop by 6-18