I find the idea of needing to shoot at all at 30 yards a bit silly. A genuine charge, as contrasted with a mock charge, from buff or ele is unlikely to start at 30 yards or more. Most likely it will happen at 20 yards or less. If I had only one shot, I would hold it until 5 yards. If I had 2 shots, I would shoot one at 15 yards and hope like hell I could bring the sights back on target for a 2nd shot at 5 yards.