What is the first step to mount the Medium Machine Gun Day Optic (MDO) on the M240B?

The first step to mount the Medium Machine Gun Day Optic (MDO) on the M240B is to open the two locking levers. This initial action is crucial as it prepares the mounting interface, allowing for the proper positioning of the optic onto the weapon system. Engaging the locking levers before placing the optic ensures that the mount's mechanism is ready to receive the optic securely. This step establishes a foundation for subsequent actions, such as inserting and securing the optic in place, which are essential for proper functionality and accuracy during operation.