To prevent confusion artillery rounds were color coded.
Solid shot left unpainted.
Case shot ( shrapnel ) painted red.
Shell painted black.
Canister painted gray.
The ammunition box in which the ammunition was shipped was also painted the color of the content.
The ammunition chests were packed at depots. The fixed ammunition for smoothbores was packed with the round facing upward. The color clearly indicating the type of round.
Oakum ( hemp fiber ) was packed solidly between the rounds.
Inside the lid is a table of fire that #6 & #7 use to determine the correct fuze setting or paper fuze. There was no need to use colored paper because the round itself was painted in the appropriate color.
Packets of fuzes & friction primers were packed on the ammunition chests. For Union 1.5 friction primers / round. CSA chest were packed with 5 friction primers / round.
During the early period of the war one regiment in the 14th Army Corps had seven distinctly different muskets.
In order to create some order out of the calico of types & calibers, not only were the ammunition chests color coded, but also the wagons of the ordinance train were colored to match.
Behind Thomas' line on December 31, 1862, an ordinance train issued out thousands of rounds to men guided by the colored wagons.