I don't know why you would need a manual. I covers more on "gun safety" than functionallity. A 686 is your basic Stainless Steel six shot revolver in .357 Magnum caliber. You can shoot .38 Specials in it if you like. New 686's have an internal lock, older models don't.
It's an excellent revolver, I bought a 686 w/6" barrel back in the 80's and I still shoot it today. I sort of favor my Colt King Cobra .357 for conceal carry, but the S&W 686 is a rock solid investement that will be in demand for another 75 years or more.