How can overheating of the M240 barrel be prevented?

Preventing overheating of the M240 barrel is crucial for maintaining the weapon's performance and ensuring safety during operation. Limiting the rate of fire is an effective strategy because it directly reduces the heat generated by the continuous firing of rounds. When the gunner controls the rate at which rounds are fired, it allows the barrel to dissipate heat more effectively between bursts, which helps prevent overheating that could lead to malfunctions or damage to the weapon.

The other options may not effectively address the issue of barrel overheating. Using only tracer rounds does not inherently prevent overheating, as they produce similar amounts of heat compared to standard rounds. Constantly aiming at stationary targets does not influence the thermal dynamics of the barrel and could lead to unnecessary ammunition expenditure, possibly contributing to overheating rather than preventing it. Frequently changing the gunner could provide short breaks for the barrel but does not address the fundamental issue of managing the heat generated during sustained firing. Therefore, controlling the rate of fire is the most direct and effective method to prevent barrel overheating.