I'm thinking I would yell and take cover then assess. If I felt it was intentional, I would probably shoot back. If the guy yells something like, I'm sorry! I didn't see you, then that is a different story and would be handled differently. My gun holds 5 but I keep at least 15 - 20 extra rounds on me just because you never know what can happen in the woods.

I've crested a hill top before on a horse only to see a guy drawn down looking through his scope as I looked at his muzzle because he heard noise and thought it was an elk coming. I was pissed to say the least and I let him know exactly what I thought about his lack of common sense and safety. He didn't say much but appoligized.