How does the seller get 1933 manufacture with a 20800 serial number? More likely late 1940s. A Model 21 Skeet Gun from 1932 trough 1935 gun would be a Tournament Grade Skeet Gun --
Winchester Model-21, Tournament Grade, Skeet Gun, 20-Gauge, 26-inch, Vent-Rib 01 12080.jpg
or a Trap Grade Skeet Gun --
WINCHESTER MODEL-21, TRAP GRADE, SKEET Gun, 12-GAUGE 01 26xx.jpg
Also, for 1932 & 3 Winchester only cataloged the Model 21 Skeet Gun with a straight grip. The pistol grip Model 21 Skeet Gun first appears in the 1934 catalogs. Most of the pre-war Model 21 Skeet Gun pistol grips were capless, like my 1941 16-gauge Standard Grade Model 21 Skeet Gun --
15561 07.jpg
but a capped pistol grip was available.
Threaded Mode