How do you perform preventative maintenance checks (PMCS) on a machine gun?

To perform preventative maintenance checks and services (PMCS) on a machine gun, conducting a series of inspections to ensure proper functioning and safety before and after use is essential. This process involves a thorough examination of the weapon to assess its operational condition, safety features, and any potential wear or damage that could affect performance.

Regular inspections allow the operator to identify issues such as dirt buildup, lubrication needs, and mechanical wear, which could potentially lead to malfunctions if not addressed. This proactive approach ensures that the machine gun is always in a state of readiness, enhancing safety for the operator and effectiveness in the field.

The other methods mentioned, such as cleaning the weapon after every use, while important, do not encompass the full scope of PMCS, which includes a variety of checks and inspections. Similarly, disassembling the entire gun regularly or testing ammunition compatibility have their own specific purposes but do not represent the comprehensive inspection process that PMCS entails. In contrast, the systematic approach represented by the correct answer is fundamental to maintaining the operational capabilities of the machine gun.