The Judas Gun — Wayne D. Overholser

For two years, thirteen men in San Lorenzo had feared the return of killer Ben Fargo. For the day they had sentenced him to rot in Canon City Prison, he had sworn to get even with them. Now Fargo had escaped and nothing could stop him. Hate in his blood, a six-shooter in his hand, Fargo was coming back for revenge -- and he wouldn't leave until he had shot his last bullet and his enemies had drowned in their own blood.