Regarding the question of the Winchester 94 receiver metal from 1964 to the early 80s, Model 94 receivers were not cast, but made from sintered compacted powdered metal. These receivers cannot be successfully reblued via conventional methods, as the sintered P/M receivers are porous -- they have approximately 10% to 14% porosity due to the interstitial space between adjacent iron powder particles. The receiver acts like a sponge and absorbs blueing bath chemicals which later leach out of the porous receiver and ruin the finish. Winchester would seal the porosity with sodium silicate and then electroplate the sealed receiver with iron in order to take the Winchester factory finish of the time period.
The sodium silicate sealing process was inconsistent and of varying effectiveness. If any residual porosity was left in the sintered P/M receiver, then the blueing bath would be absorbed and later leach out. It was not uncommon to unpack a new Win 94 from the 60s and 70s and find gray streaks or rusty streaks or spots in the blueing on the receiver. Gunsmiths went nuts trying to get their hot blue to "take" on a 1964-1982 Win 94 receiver, and most 'smiths gave up and refused to refinish W94s. A few 'smiths took to using oven-cured or anerobically-cured methacrylate resin to seal residual porosity, and this process was fairly successful at holding out blueing chemicals.
Winchester abandoned the sintered powdered metal receiver in 1982 (or maybe 1981 for the 1982 model year, I can't recall) about the time the 1894 Big Bore was introduced, and went back to forged receivers.
Source? Direct experience in the P/M industry and two personal friends who were "present at the creation" for the P/M W94 receiver in the early 1960s.
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