A short wall on either side of you with something to insulate works well too. All you need to do is to get the sound moving in a direction that isn't directly toward the bystanders. If you've blocked the line of sight, you've blocked the sound. You'll always have reflection, but it's nothing like the direct blast.
Its funny, I was at a friends house last night and his property and mine are visible from each other over a ravine. They are just over a mile apart, call it 1.2. He asked me about hunting season and I said I hadn't hunted. He asked, who shot up across the mountain on the first Saturday. I said I had no idea, I didn't think anyone had, and perhaps it was the neighbors. He was pretty adamant telling me how unmistakable the sound is coming from this property. He's not talking about the gun blast, he's talking about the bullet noise. I used to regularly shoot on my 400 yard range here and had people say they could clearly hear the bullets from 3 miles away. Most thought it was an awesome sound, but, I am sure it would get old after a while.