Protecting the components
The glider requires only eight additional transitions in its definition, and tolerates crowding by the bistable cells. Nevertheless, the bare gun is susceptible to interference from gliders striking it from the right. Wraparound resulting in the evolution of a cyclic ring will practically guarantee that the glider gun will shoot itself down. Moreover, if there are several glider guns, each will surely attack its neighbor. Defenses can be constructed with the help of transitions as yet undefined.
Harold V. McIntosh