By definition a Model 21 G2190B came with a checkered butt.
The Model 21 Skeet Gun came out during 1932 but didn't make it into the 1932 catalog, but Winchester put out flyers.
In the 1933 Winchester catalogs the Model 21 Skeet Gun was only offered with a straight grip. The big 1933 catalog --
1933 Model 21 Skeet Gun, big catalog.jpeg
the 1933 pocket catalog --
1933 Model 21 Skeet Gun, Pocket catalog.jpeg
By the 1934 Winchester catalogs they added a pistol grip Model 21 Skeet Gun. The big 1934 Winchester catalog --
1934 Model 21 Skeet Gun, Big Catalog.jpeg
From the 1934 Winchester pocket catalog --
1934 Model 21 Skeet Gun, Straight Grip, Pocket Catalog.jpeg
1934 Model 21 Skeet Gun, Pistol Grip, Pocket Catalog.jpeg
They all list a checkered butt.