What type of ammunition is NOT suitable for the M240 in all situations?

The use of tracer rounds in the context of the M240 machine gun can be limited due to specific operational circumstances. Tracer rounds are designed to produce a visible trace of the projectile's path, which can be beneficial for aiming and adjusting fire, particularly in low visibility conditions or during training exercises. However, they can also reveal the shooter's position to the enemy, making them less suitable for stealth operations or situations where concealment is critical.

The potential for tracers to compromise the element of surprise or to inadvertently direct enemy fire towards the firer makes them less versatile compared to standard, blank, or armor-piercing rounds. Standard rounds are reliable for general use, blank rounds are used for training and practice without live ammunition, and armor-piercing rounds are designed for penetrating tough targets. The operational context is crucial when determining the suitability of ammunition types, hence tracers may not be the best choice in all scenarios.