A method for securing an implantable medical device within a receptacle of a delivery catheter, the method comprising: retracting the receptacle of the delivery catheter relative to an inner shaft of the delivery catheter so that a distal-most opening of an elongate lumen of the inner shaft is exposed at, or distal to, a distal-most opening of the receptacle; inserting an elongate snare mandrel into the lumen of the inner shaft of the delivery catheter so that a hook of the snare mandrel protrudes from the exposed distal-most opening of the inner shaft and a proximal end of the snare mandrel protrudes from a proximal port opening of the delivery catheter; engaging the hook of the snare mandrel with a proximal portion of a tether that protrudes from a proximal end of a tether support shaft, the tether extending within a lumen of the support shaft, and a distal portion of the tether protruding from a distal end of the support shaft and being coupled to the medical device; applying a pull force to the proximal end of the inserted snare mandrel, after engaging the hook thereof, to pull the support shaft into the lumen of the delivery catheter inner shaft so that the coupled medical device comes into engagement with a flared end of the delivery catheter inner shaft, the flared end surrounding the distal-most opening of the inner shaft lumen; locking the proximal portion of the tether within the delivery catheter after applying the pull force; and advancing the receptacle of the delivery catheter, relative to the inner shaft thereof, over the medical device so that the device is contained within the receptacle, after locking the proximal portion of the tether. retracting the receptacle of the delivery catheter relative to an inner shaft of the delivery catheter so that a distal-most opening of an elongate lumen of the inner shaft is exposed at, or distal to, a distal-most opening of the receptacle; inserting an elongate snare mandrel into the lumen of the inner shaft of the delivery catheter so that a hook of the snare mandrel protrudes from the exposed distal-most opening of the inner shaft and a proximal end of the snare mandrel protrudes from a proximal port opening of the delivery catheter; engaging the hook of the snare mandrel with a proximal portion of a tether that protrudes from a proximal end of a tether support shaft, the tether extending within a lumen of the support shaft, and a distal portion of the tether protruding from a distal end of the support shaft and being coupled to the medical device; applying a pull force to the proximal end of the inserted snare mandrel, after engaging the hook thereof, to pull the support shaft into the lumen of the delivery catheter inner shaft so that the coupled medical device comes into engagement with a flared end of the delivery catheter inner shaft, the flared end surrounding the distal-most opening of the inner shaft lumen; locking the proximal portion of the tether within the delivery catheter after applying the pull force; and advancing the receptacle of the delivery catheter, relative to the inner shaft thereof, over the medical device so that the device is contained within the receptacle, after locking the proximal portion of the tether.