Release mechanism for medical device includes a bushing having a proximal end, a distal end and a channel extending therethrough. Plurality of extend proximally from the distal end are biased toward a release configuration in which engagement surfaces at distal ends thereof retract radially into the channel. A core pin insertable through the channel applies a radially expansive pressure to move the arms radially outward to a locking configuration. Engagement surfaces of the first and second arms connect to a retaining surface of a tissue treatment device containing capsule, which extends at an angle relative to the engagement surfaces selected so that a first portion of a force transmitted along an axis of the bushing moves the arms radially inward toward the release configuration before a second portion of the force exceeds a threshold level associated with the removal of a tissue treatment device from gripped tissue.
