welcome to the Forum...normally a red ( plum) color of regular steel used in guns IS indeed a sign of an improper temperature in the bluing process, in the case of Winchester guns from LONG ago that were using "nickel steel" they too would or could turn "reddish" or plum when reblued as Winchester did their process much higher temps and longer so it did NOT turn "plum", along comes Ruger and the FACT that they used "castings" for most of their parts and these castings were made up of a 4140 chrome -moly steel, good for use in firearms....BUT the issue was improper mixing of the "batch" of the alloy make up, so if not mixed or improper amounts of various metal additives, the blue would NOT take, maybe get "lightening streaks in and near the surface, as any metallurgist knows some of the metals do NOT blue ( oxidize) well so stay "clear, or lighter color ,usually reddish.....Ruger collectors have liked'; ( some loved) this anomoly,BUT other gun people frowned on it as they felt it was "wrong" defective, and they are right,,,same also goes for guns that were "seconds" of Ruger, and forwhatever reason "why" if returned, found to be defective, they were stamped with the letter "S"....again, a Ruger collectors "love" and the chase to find one of these guns as it is indeed a "variation" and is rare to come across,BUT a love to collect "defects"??? go figure, it is a bit odd and strange.....the search goes on...
BY the way there are letter "S" used on Ruger cylinders as a "proof mark" that the gun was "proof tested ( fired) so this "S", is NOT the rare marked type.....all part of Ruger lore and can be found in the many different books written by Ruger collectors and enthusiast over the years....my knowing of and having to deal with the "bluing " process is I have owned 3 different shops over the years, and we refinished/restored firearms , since the early 1970s ( Cleveland Bluing Co.,),,,,and the "batch" information comes from my friend Jim Hoobler who was, years ago the man who ran their casting plant ( Pinetree castings),,,then onto doing the Titanium castings for Ruger and now retired, bless his heart ,,,,,last saw him in Tulsa years ago......hope this helps .... Happy New Year........


