U.S. Army FM 3-22.31 40mm Grenade Launcher M203 February 2003 - version 2.pdf.

An effective overall training strategy produces well-trained grenadiers and trainers by
integrating resources into an effective year-round training program. Beginning with IET
and continuing both in other institutions (NCOES, IOBC, and IOAC) and in the unit,
such a program trains and sustains the individual and collective skills needed to perform
the wartime mission. Specific training strategies are implemented by institutional and
unit training programs, and supporting training strategies are implemented through the
use of other resources such as publications, ranges, ammunition, training aids, devices,
simulators, and simulations. The year-round program includes periodic preliminary
marksmanship training followed by zeroing and range qualification firing. Other key
elements of the program are training for the trainers and refresher training for nonfiring
skills.