A medical device includes (a) a capsule including a lumen extending therethrough, a proximal end of the capsule including at least one window extending therethrough; (b) a bushing including a channel extending therethrough, a distal end including at least one arm extending distally therefrom such that a corresponding one of the arms is releasably engagable with a corresponding one of the windows; and (c) a core member including a locking portion and at least one engaging element. The locking portion is sized and shaped to be received within the channel of the bushing to apply a pressure to the arm such that the arm engages the windows. The engaging element extends laterally outward from a portion of the core member such that the engaging element engages a corresponding one of the arms to deform the arms radially inward and out of engagement with the windows.