Might sell them here? No FFL dealer needed, but the title and the postage have to be considered, and you'll need to describe the book's condition precisely and maybe provide photos.
Or, get a copy of Sporting Classics and contact the book dealers who advertise there. They're more into classic hunting and fishing books but might buy what you have. And if they're selling a title that you have, you can use their price for a reference.
Don't just sell to a used book store for a pittance, if you have anything good and maybe old.