Manufactured 1927, this is a very interesting, likely factory prototype for a lever action version of Winchester's popular Model 90 .22 caliber rifle. Two other examples very similar to this one are pictured and described on p. 195 of "Winchester's Slide-Action Rifles Vol. I: Model 1890 & Model 1906" by Ned Schwing. The previously mentioned page notes that the designs were made by William Mason as early as 1889 and were finally patented in 1906. They share many similarities with the standard slide action Model 1890, and the only visible difference between this example and the two pictured is a screw on the left side of the frame, which this example lacks. The rifle has standard markings including Winchester factory oval proofs on the barrel and receiver at the breech. The lever action mechanism has the appearances of factory work.