The 680 Ultralight used an aluminum alloy receiver with a titanium insert in the breech face. They are easy to identify. The vast majority of 680 receivers, however, are made of steel and Beretta has used a variety of finishes: Blued (matte and satin), Bruniton (a black, Teflon-based coating found on the 682 Super Sport and X models), Greystone (titanium nitrate based - found on 682 and ASE guns of a certain vintage), brushed chrome, and electroless nickel plating. Cole uses the basic black-framed guns as the basis for his case-hardened custom guns. Turnbull case-hardened Cole's early custom guns. I am not sure if this is still the case.
