Owner's manuals tell you everything you need to know for the safe handling, loading, unloading, disassembly, cleaning, and lubrication of the firearm. I read them on every new gun I purchase or sell. I also highly encourage customers to read the manual, specifically any red letter statements and warnings.
At least half of our customers are new owners or haven't owned the current model they buy. Plus gun manuals can be looked up on company websites or ordered directly.
I did have a problem with magnum research at first when I asked for a copy of the desert eagle manual. I had two desert eagles and no manual, and they wanted me to buy a manual for $20, but when I suggested that a lawyer would love to hear that if I accidentally injured myself do to not having a manual, I was sent one free of charge. (I did have the serial numbers of both to prove I owned them and not just some fanboy looking for deagle swag)