Lights Out by David Crawford.
"Downloaded from the internet over three million times, this exciting, action-packed, survival story is finally available in book form. Lights Out chronicles the challenges of Mark “Karate Man” Turner when the lights go out over most of the free world. He must find in himself the ability to unite his family, friends, and neighbors if any of them are to survive the harsh reality that everyday life becomes when the veneer of civilization is stripped away."
The story is about everyday survival after a major EMP attack that sends the country into the dark. I mention it here because it is chock full of detailed gun content. In fact it has characters discussing the relative utility and practical use of all kind of firearms from small .22 revolvers, to 1911's, Glocks, AK47s, ARs, BMG .50's and a lot more.
It's a good story as well. I read the first 10 chapters online. I was hooked and had to buy one!
--Buy a copy. Good stuff!