Ready service ammunition is that

ammunition Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...

located in close proximity to a military or naval gun and is stored in such a manner that it is ready for quick use. Boxes located near a gun are sometimes termed ready boxes. They are designed to keep a small amount of ammunition dry and free of contaminants while affording ready access by gun crews. Larger amounts of ammunition that would not be immediately used in an emergency situation are normally stored in an ammunition magazine away from the immediate area of use for safety reasons as well as to keep the ammunition free from environmental contamination.

References

;Footnotes ;Bibliography * {{Cite book , last=Cutler , first=Deborah W. , url=http://worldcat.org/oclc/1341887903 , title=Dictionary of Naval Terms , last2=Cutler , first2=Thomas J , publisher=Naval Institute Press , year=2005 , isbn=1-59114-150-8 , location=Annapolis, Maryland , oclc=1341887903 Military logistics