Mc, you asked what a "Ghost Ring" is. It is simply a large apature, when looking through it, it sort of "grays-out", or in other words, it is not very obvious or visible. Lots of folks simply do not use any inserts in the peep sight, just the large threaded ring. I think "Rife" ( or maybe "Handloader") magazine tested various openings, and found that for practical shooting, the size does not matter much, accuracy wise. The large opening is quick to aquire, and is easy to see through in poor light. BUT, for woodchuck hunting with your Hornet, you might try different inserts, to see what works best for you, since you probably will not be taking shots at running game, or charging critters!!
Mark