I'll just throw this out.......
While many tout Brass faced hammers for G'smithing, I have not been a Fan and here is why. I find that if I want a "soft face" hammer, any of the Yellow Plastic, Trusty Cook Red Plastic, Delrin, Nylon type work excellent and they will NOT mar. For use with a Punch, a small regular Steel Ball Peen hammer is perfect as the face of the hammer is only striking the Punch, not the pin or gun itself.
Brass hammers deform quickly, develop burrs and dents and they can leave gold colored marks on metal. While the discoloration can be removed, I choose not to be bothered as it's a P.I.T.A.
While we are on the subject, I also pretty much stopped using Brass Punches for the same reasons. If I need a soft faced punch, I choose one of the Nylon Tipped Steel Punches Brownell's sells. For most applications my Starrett Steel Punches or Steel Roll Pin Punches are used.
Note: I find that Steel punches do NOT mark up a guns surface IF THEY ARE properly cared for. By that I mean kept "dressed" flat and burr free. the worst thing you could do is to use a Burred, disfigured face punch on anything - which will more than likely leave marks on metal.