Triggerman

Triggerman by J. F. Bone - The essential requirements of a first-class triggerman are two: that he know how to pull the trigger–and when not to! 

Jesse Franklin Bone was born in Tacoma Washington in 1916. Before he was an author Bone was a veterinarian, and a professor of veterinary medicine, served in the U.S. Army Veterinary Corps, attaining the rank of lieutenant colonel and retiring in 1976. His first short story, Survival Type, didn't appear in Galaxy Science Fiction until he was 41, in 1957. 

About 30 short stories and 5 novels later his 21 year career as an author came to an end. Triggerman first appeared in Astounding Science Fiction in December 1958. It was in Astounding in the UK in March of 1959. Three months later it could be found in the Dell Paperback The Year’s Greatest Science Fiction and Fantasy: 4th Annual Volume and almost 30 other publications around the world.

Which would lead you to believe that this is a really good story. It is, so much so that it was nominated for the Hugo Award for Best Short Story in 1959.