The trails are on the north side of the park. You will enter from the south, go left over the spillway to the shelters. Part of the trailheads will be further up the road to the north. The firing range is to the northwest of the park. The range is not used all the time so odds are good it will not be a noise distraction. If they are using it the further east along the trails you go the less noticeable it will be. I have camped out there many weekends and never heard a shot fired.
http://www.tpwd.state.tx.us/publicat...p4503_103f.pdf