I agree with you PaintLuver. It is a saddle sore. That was the reason I asked how long they've had the horse, because I didn't want to scold them if it wasn't their fault... which indeed it was not. Either the previous owners were careless, or he's a difficult horse to fit. I lean toward the former, but who knows. Just be cautious that whatever saddle you use on him REALLY fits and that you keep it in the right position. We need better "conformation style" photos to help you with that part though. But he is a cutie.
ACC