Why is it important to know the weapon’s gas system type (direct impingement vs. piston) for maintenance planning?

• A. It has no impact on maintenance planning.
• B. It determines the brand of ammunition that can be used.
• C. Direct impingement and piston systems foul in different locations and require distinct cleaning and lubrication routines; affects maintenance frequency.
• D. It only affects the weapon's weight.

Answer: (C)