Join Date: Sep 2008
Location: Bavaria, Germany - the center of 15th and 16th century gunmaking
Not only is this a wheellock spanner but a combination tool, in that its flattened lower end acted as a screwdriver! The ring was for a attaching a suspension cord.
Moreover, the round hole was meant to measure and identify the caliber of the lead balls used (caliber gauge, German: Kugellehre); its small diameter denotes that the spanner once accompanied a pistol or carbine.
Tools of this kind can be dated to the Thirty Years War era (1618-48).