There is a very good reason that very, very few shots are attempted at more than 300 yards in Africa. The PH is watching, and every animal hit equals a trophy fee paid, no matter if the animal is brought to bag or not. It's no great mystery that behaviour changes when there are real consequences. Sadly, nobody watches in North America.......
That's an interesting point about long range shots in Africa, but I can't agree that it's sad that there's not always someone watching here. Given the choice, I'll take no one looking over my shoulder, and no requirement for a PH or guide.
