Outlaw's Gun — J.R. Roberts

Clint is tracked down by an outlaw who, in his fifties, finds that his gun is slowing down. He wants Clint to use his gunsmithing abilities to make him a new gun, one that will increase his speed and, hopefully, shave a few years off his gun hand. Months later, Clint learns he's been made a fool of. The outlaw is using his newfound speed and accuracy with a gun to settle some old scores—and some new ones. It falls to Clint to stop him, and to see if the outlaw's abilities with a gun match his own.