Retainers for holding tools and methods for controlling the motion of a locking member, such as a resiliently-biased locking ball, in a retainer. The locking member is disposed in a passage that intersects another passage configured to receive the tool. A portion of the locking member has a contacting relationship with the tool in order to hold the tool within its passage. The retainer further includes a constraint member, which may be a threaded member or a non-threaded member, that occludes the passage containing the locking member. During a stamping operation using the tool, the constraint member mechanically constrains motion of the locking member within its passage by contact with the locking member.