Aluminum casings are typically anodized but may also be unfinished.
Anodized casings can come in a variety of colors including red, orange, gold, green, brown, blue, and purple etc.
Drawing is probably the most common method of constructing casings.
However, metal casings have also been constructed by riveting or fastening the head to a coil of sheet metal that forms the body (Figure 5).
Recoilless casings that allow gas to pass through the base are normally closed with a fiber base.
The casings that allow gas to pass through their walls are lined with a combustible liner to hold the propellant and protect it from moisture.
Winchester used a combination of drawing and riveting to construct shell casings in the late 1880s and 1890s (Figure 5).
These casings had a have drawn walls and a two-piece head that is attached with rivets. From left to right: Photos 1 and 2 show the side and base of a coiled, three-piece, 37mm Hotchkiss [37x94R] casing; note the three rivets holding the casing together.
The primers in recoilless cases are in the center of the base for the casings with perforated sides and are in the base or on the sides for casings with blow-out bottoms.
Figure 7 shows examples of recoilless shell casings. From left to right: Experimental 6-pounder Davis recoilless with primer on the side , base of the 6-pounder Davis showing the notch to line it up in the gun, 90mm recoilless [90X397R] with fiber base and primer in the base, 106mm recoilless shell casing [105x607R] .
Often a collector encounters shell casings that have been altered.
Sometimes alterations are legitimate military alterations made for experiments (Figure 8); sometimes the casings are altered to make blanks (Figure 9); and sometimes they have been altered to make "trench art" such as umbrella stands, pencil holders, vases, and lamps (Figure 10).
The propellant is packed into a shell casing or a combustible bag (a powder bag).