In his accompanying letter, Winchester expert and author Herbert Houze explains how he determined that this shotgun is "no doubt" a Winchester .410 slide action model room prototype which "can be considered a legitimate precursor to what became known as the Winchester Model 42." The absence of markings, finished in the white and the appearance of tool marks "is consistent with the Winchester Model Room's policy of producing fully functional models to demonstrate the working operations of designs under consideration for further development of production without undue consideration of their exterior finish" as observed on Winchester prototypes held at the Cody Firearms Museum. For dating this shotgun Houze pointed to "the gently stepped rear portion of the rear upper receiver" which has been observed on sample models built in the late 1890s and early 1900s that demonstrate design ideas developed by Winchester chief designers Thomas C. Johnson or William Mason. Moreover, factory developmental design drawings (photocopies included) circa 1919-1920 illustrate specific features found on this shotgun such as the hammer spring guide pin, cartridge spring guide screw, trigger and breech bolt. The receiver was likely originally built circa 1900-1901 for an abandoned prototype chambered in .32 or .38 caliber and then reused for the making of this .410 bore prototype circa 1919-1920, concluded Houze. The front loading tube fed magazine shotgun has a 2 inch chamber. Production Model 42s were chambered for the new 3 inch shells as well as the 2 1/2 inch shells. The smooth pistol grip stock lacks a buttplate, and the forearm has 17 grooves. Introduced in 1933, the Model 42 was the first mass production pump gun specifically designed for the .410 bore and was the brainchild of Winchester’s chief design engineer William Roemer (1886-1953). The Model 42 was a great success because Roemer was able to develop a pump action that properly accepted the .410 shell, an achievement that alluded others and awarded him with many patents pertaining to its design. As Houze notes, “The light weight of the gun, combined with its effective cartridge, made the model an instant success” (“Winchester Repeating Arms Company” page 220). In conjunction with the Model 70, the Model 42 represented Winchester’s best technological triumphs prior to World War II. Over 9,000 Model 42s were sold in its introductory year, a crowning achievement in itself, especially when considering sales were during the Great Depression. Roemer’s involvement in the development of the Model 42 began in 1928. It is not out of the realm of possibility that Roemer handled and analyzed this tool room prototype during his effort to design his highly successful slide action .410 bore shotgun.