So 100 yards is a good rule of thumb unless it isn't and the hog runs a half mile. Wow!
You know, I think if you shoot through the shield areas that "closing up" as you mentioned really does occur, sort of like self sealing fuel tanks. It isn't always perfect, but does seem to happen. See post 18 here http://thefiringline.com/forums/show...ght=mulefooted