Wow, some great suggestions!
I, too, love physical volumes. I worked many years as a librarian, and many of my favorites were found by browsing shelves and discovering treasures.
That said, electronic books give me a way to expand my library without pushing us out of the house. I converted our "formal living room" into a comfortable library, with a wall of books, but we finally ran out of space.
I mentioned Gutenberg, Gutenberg Australia, and archive.org, but another free source of reading material is
Baen books (
www.baen.com/). All of their content is DRM-free (Digital Rights Management), which means that once you own it, you are free to do whatever you want with it. They offer a variety of formats for download, as well. I like books on laptops and iPads, so I can read during lunch breaks at work.
They have free stuff! At their
Free Library section, download anything you want. Gun content wise, they have for free several books, including a favorite of mine:
Monster Hunter International, by Larry Correia, which starts with a gun-toting accountant being attacked by a supernatural creature. As a bonus, there's a "
Monster Hunter Ballad" on YouTube that you might find amusing.
Another fun book is
Freehold, by Michael Z. Williamson, a guy who makes knives, swords, and AK-47s (actually AKMs, if it matters) for fun. Also lots of fun is John Ringo's
Gust Front, the first book of his extensive series about the invasion of earth by the horrific Posleen. Another book in the series --
A Hymn Before Battle -- is also free to download. David Drake has several free titles, including a science fiction work about mercenaries protecting a colony --
Redliners -- that I really enjoyed.
Everything is linked for your convenience. I hope you enjoy them!
All my best,
Dirty Bob