I used to do that hike regularly before I started shooting at Koko Head. It does seem like the range is VERY close when you're walking along the paved road that runs around the upper baseball field, but I never hear any whizzing of projectiles anywhere when I was on the trail. In fact, once you get up beyond the bridge, you don't really hear shots from the range that much, particularly if it's windy.
I've seen tons of people get taken off the trail by HFD helicopter. I've always wondered what, if anything, they are charged for that service. When I used to snowboard in WA state, a couple resorts had signs at the boundary of the ski area warning that the area beyond is NOT part of the area that is patrolled and that there is a minimum fine of $1000 (or something like that) if they have to go in there to get you out.