I can get into this one a bit, I listen to books much more than read these days. I can listen in the shop while working where reading itself takes far more time that I just don't have. I used to be a heavy reader though years ago.
On the gun front one of my favorite authors is Stephen Hunter, he typically gets the guns right. Which is something that can't be said for just about any other author;) If he puts something in his books happening with a firearm there is a fairly good chance he's actually tried it in the real world to see if it works that way etc. Excellent fun reads in my opinion.
Another gun guy who's an author I enjoy is Larry Correia he's got a different style that can be off putting for some, myself included in the start. The only reason I think is that they aren't typically written like most authors there is something different. That said these are more of a science fiction or something like that which is off my normal beaten track in some ways. He does the Monster Hunter series and I'd say they are more based in reality than most, no sparkly vampires etc. More of if vampires existed this is how they would function and why sort of approach. Not without fault like anything but I enjoy his books(and sort of know him via other friends). Also I find his Hard Magic series to be really good, very interesting world he's created and worth a listen.
Michael Crichton hard to go wrong with virtually anything he wrote before his death. The last few posthumous releases were a bit more dodgy. None the less he got me into reading heavily when I was younger, and I've read everything he wrote from fiction to non fiction over the years and I've enjoyed it allot. Particular interest of mine is how close to reality he was predicting things way ahead of time. For instance Congo is old, like 78ish? from memory and the technology he's describing is way ahead of the curve. And most of his books follow this path and that has always impressed me, very smart dude and a good researcher in allot of cases.
There are others but I don't have more time to type so another day;) But I'll also go through the above two posts and take a look at those since I'm always looking for new books and authors. Of the three listed above, of course one died, and the other two write one or so books a year. So not allot of guaranteed good new content;)
Luke