Which tool is NOT used for the assembly and disassembly of the breech?

The torque wrench is primarily used for applying a specific torque to fasteners, ensuring that bolts and nuts are tightened to a precise specification. However, in the context of the assembly and disassembly of the breech of the M777A2 Howitzer, the other tools are specifically designed for tasks related to manipulating the breech itself, either by holding components securely in place or providing the appropriate leverage to remove or install parts.

The 24mm socket is used to fit over and turn fasteners, facilitating the assembly or disassembly process. The breech stool supports the breech during these operations, making it easier and safer for the crew to manage the heavy and complex components involved. The firing mech wrench is tailored specifically for the unique shapes and requirements of the firing mechanism, aiding in proper installation and adjustments.

Thus, while all tools are vital in the broader context of maintenance and operation activities, the torque wrench is not a primary tool for directly assembling or disassembling the breech itself, making it the correct answer to the question regarding which tool is not used for this specific task.