What is the name of this movie?

It's about a man go goes after those who murdered his family, I believe it was his daughter and wife. He goes and kills them by buying guns from the murderer's father, but the father knows, so he let's him buy the guns anyway. It might be a son, I think...I remembered he got his throat slit in a gas station? Please help. It was really good. At the end there's a shootout.