From 22-caliber pistol rounds to the huge shells thrown by heavy artillery pieces, there is enormous variation in the types and purpose of ordnance in use by militaries, police forces and civilians around the world. There is almost as much variation in the containers used to store it. These differ based on size and weight, but also on purpose, with some containers being expendable and constructed for a single use while others can keep their contents safe for decades.
Ammo Cans
The term "ammo can" is generally used to refer to military ammunition storage boxes made of metal. They are usually filled with ammunition and sealed at the factory. Ammo cans are intended to be opened immediately prior to use and discarded as soon as they have been emptied of their contents. Ammo cans will usually have the type and orientation of the ammunition within them stenciled onto their surfaces, as well as the manufacturer and lot number. There are a variety of sizes and shapes designed to accommodate different types and sizes of small-arms ammunition, as well as different ways of storing the ammunition within.
Ammo Boxes
"Ammo box" generally refers to a box similar in construction to an ammo can minus a few key differences. Ammo boxes are typically designed for reuse when recovery of the used box is practicable. They usually have a resealable lid that is held onto the box by means of several clamps around the edge. Some ammo boxes are made of wood, and these typically use a latch mechanism rather than clamps to hold the lid closed. All ammo boxes include a means to facilitate carrying them. Metal ammo boxes typically have metal handles built into the top or sides, while wooden ones often have a leather or plastic strap for a handle. Ammo boxes are used to contain ammunition for all different types of small arms, from pistols to belt-fed machine guns as well as grenades. There has also been interest in using fiberglass for making ammo boxes to take advantage of that material's light weight.
Heavy Ordinance
There is a dizzying array of storage solutions for ordinance types beyond the small-arms scale. Artillery projectiles are often shipped and transported in cylindrical metal cans, each containing a single shell. 20-mm and larger sized cannon ammo for rapid-fire guns can be stored in large metal boxes similar to those in use for small-arms ammo, except that the boxes are usually larger and of heavier construction.