A loading unit includes a shell assembly, a lock collar, and a release collar. The shell assembly has a coupling ring that defines a lock slot and a proximal opening configured to receive a distal end portion of a surgical instrument. The lock collar is disposed about the coupling ring and has a radially extending lock that is configured to be received within the lock slot. The lock collar is transitionable between a locked configuration in which the lock is positioned within the lock slot and an unlocked configuration in which the lock is lifted from within the lock slot. The release collar is disposed about the coupling ring proximal of the lock collar and is transitionable between an unactuated position and an actuated position. The release collar transitioning the lock collar to the unlocked configuration as the release collar is translated from the unactutated position towards the actuated position.
