charges for the 40-mm and the 3-inch guns are issued completely   assembled,   with   no   replacement components. Bag  Charge In  large  guns  (8-inch)  using  separate  loading ammunition, the propellant charge is made up of sections of powder contained in cylindrical cloth bags that approximate the inside diameter of the gun chamber in which they are to be used. In most cases, more than one section (bag) is required. For example, the 8-inch, 55-caliber gun uses a propellant charge consisting of two  sections;  the  16-inch,  50-caliber  gun  uses  a propellant charge of six sections (fig. 6-4, view B). In these guns the leaking of gases from the chamber is checked by the mushroom and pads on the breech plug. The breech plug also contains a lock, which receives the separately  loaded  primer. Fuzes Fuzes  are  the  components  that  set  off  the  projectile bursting charge. No matter how complicated or simple the construction or function of the fuzes, they always serve  the  same  purpose. All fuzes use the force of inertia for arming and, in most  cases,  operation.  Each  type  of  fuze  has  a  different tactical  use.  The  use  and  a  detailed  functional description will not be covered in this text. For more information on ammunition types and their fuzes, refer to Navy Gun Ammunition, SW030-AA-MMO-010. Fuzes can be generally classified by function, as discussed  in  the  following  paragraphs. TIME FUZES.—Mechanical time fuzes (MTFs) function a predetermined length of time after the projectile is fired. The exact time is set before the projectile is loaded into the chamber, by a mechanical fuze setter on the mount, or you can set the fuze with a special fuze wrench. The interval between the instant the fuze is set and the instant the projectile is fired is dead time. No matter when, how, or by what it is set, the timing mechanism of a time fuze will not function until the  projectile  is  fired. PROXIMITY  FUZES.—Proximity (variable time (VT)) fuzes are energized after the projectile is fired and function  when  the  projectile  nears  the  target. PERCUSSION  FUZES.—Percussion  (impact) fuzes function as the projectile strikes the target or (especially an armor-piercing projectile) after the projectile penetrates. Some fuzes (nondelay type) function  immediately  on  contact  with  any  thin  material (for example, the thin sheet metal skin of an aircraft). Fuzes for armor-piercing projectiles, however, always incorporate a slight delay to keep the burster from going off until after penetration. These percussion fuzes can be located either on the nose (PDF) or on the base (BDF) of  the  projectile. COMBINATION FUZES.—Combination  fuzes incorporate both time and percussion features; that is, the fuzes may go off either on impact or after the time set,  whichever  occurs  first. AUXILIARY   DETONATING   FUZES.— Auxiliary detonating fuzes (ADF), as the name implies, operate only with other fuzes. In gun projectiles, they form  part  of  the  explosive  train  and  pass  on  the explosion initiated by another fuze (located in the projectile  nose)  to  the  main  bursting  charge. MAGAZINES The term magazine applies to any compartment, space, or locker that is used or is intended to be used for the  stowage  of  explosives  or  ammunition  of  any  kind. The term  magazine  area  includes the compartment, spaces, or passages on board ship that contain magazine entrances and that are intended to be used for the handling and passing of ammunition. The term is also used to denote areas adjacent to, or surrounding, explosive stowages, including loaded ammunition lighters,  trucks,  and  railroad  cars,  where  applicable safety  measures  are  required. Magazines are arranged with regard to ease of supply, the best obtainable protection, and the most favorable  stowage  conditions. Magazine  Types Many  different  types  of  magazines  are  provided  on ships. Each magazine is designed specifically for the type of ammunition it is to contain. For our purpose, however, we will be concerned with only three types: primary  magazine,  ready-service  magazine,  and ready-service   stowage. PRIMARY   MAGAZINES.—Primary    magazines are designed as ammunition stowage spaces generally located below the main deck and, if possible, below the waterline.   They   are   adequately   equipped   with insulation,  ventilation,  and  sprinkler  systems.  These spaces must be provided with fittings so that they may be  securely  locked.  Primary  magazines  accommodate  a 6-7