The objective of this manual is to allow the reader to be able to use the various M203 40mm grenade launching weapons competently. The manual will give the reader background/specifications of the weapon, instructions on its operation, disassembly and assembly; proper firing procedure; and malfunction/misfire procedures. Operator-level maintenance will also be detailed to allow the reader to understand and become competent in the use and maintenance of the M203 Grenade Launcher.