"Rifles for Watie" is a very enjoyable, easy read. Historical fiction based on the US Civil War.
Also, not specifically about guns, but as an author who focused much of his career on humor relating to the outdoors (hunting, fishing, camping, etc), Patrick F. McManus is a downright superb storyteller. He has several collections of short stories, which follow:
1. "A Fine and Pleasant Misery"
2. "They Shoot Canoes, Don't They?"
3. "The Grasshopper Trap"
4. "Into the Twilight, Endlessly Grousing"
5. "Never Sniff a Gift Fish"
If I recall correctly, McManus still writes for Field and Stream on occasion. I know he did up until a few years ago. Generally short, humorous stories on the last page. The first section I always flipped to.