No Finger on the Trigger — J.T. Edson

When the Fuente brothers learned that Waxahachie Smith was investigating their criminal activities, they decided that drastic action was called for. As far as they were concerned, the best way to stop a Texas Ranger -- short of killing him -- was to have his trigger-fingers cut off!
That was a mistake. For Waxahachie Smith was not the kind of man to accept defeat.
Converting his Colt Peacemaker into a ‘slip gun', and learning a whole new technique for drawing it, Smith acquired an even faster and more deadly skill. Then he went back to finish the job he'd started ...