A pivoting accessory mount used for attaching auxiliary devices such as sighting devices to a firearm. The accessory mount includes a base member that attaches to the firearm and includes a mounting support and a shaft. An accessory receiver is pivotally received and retained about the shaft. The accessory receiver is pivotable between an inactive position along the side of the upper receiver of the firearm and an active position extending substantially vertically relative to and in alignment with the upper receiver of the firearm. The mounting shaft is linearly displaceable, thereby engaging the accessory receiver when in the active position to prevent accidental displacement of the accessory receiver.