Moon of Cobre (A William R. Cox Western Classic Book 1‪)‬

Matt Buxton was a good man who built an empire out of prairie dust. And Matt was loyal to his own—even his rowdy brother Jed, who fought too often and drank too much. He was so loyal that when Jed shot a girl in the back, he was willing to wreck his own town and start a range war to save Jed's hell-bent neck from the rope.
What he didn't count on was Marshal Hancock, the lawman who believed in law, and the girl's mother who'd just arrived from the East and she would do anything for revenge.