Various exemplary embodiments of a retainer system for a ground engaging tool. In one exemplary embodiment, the retainer system may include a lock configured to receive a portion of a support member to be locked with the ground engaging tool and a retainer bushing including an inner surface configured to rotatably receive the lock. The lock may be rotatable relative to the inner surface of the retainer bushing between an unlocked position and a locked position. The retainer system may also include a plug configured to substantially fill at least a space between the lock and the inner surface of the retainer bushing when the lock is in the locked position.