This scarce and desirable set of Winchester tool room parts and gauges was assembled for development and standardization in production of the Model 1890, and subsequently the Model 1906, slide action rifles. These pieces would have been used to ensure that manufacturing tolerances and interchangeability of parts was maintained. These sorts of tool room sets were extremely valuable during production as they established the standard to which all other parts should be held. Many of these pieces are tagged with notes directly from the tool room at the Winchester factory detailing what the pieces are and changes that have been made during development. Includes one receiver of the later takedown pattern with a short section of barrel attached, four additional short barrel sections, a longer 20 1/2 inch barrel section marked "MOD./1906", six bolts in various stages of completion, two bolt carriers, two magazines, a metal "M 06" marked slide handle, multiple cartridge stops from both models with tags listing development changes, an "original" and "new model" 1890 trigger, two firing pins, various springs, and a plethora of other small parts. The entire set of parts is contained in a hardwood, glass-topped, display case with tags attached to many of the pieces.