The A "Standard" Grade had American Walnut stock and forearm. The B "Special" Grade and the C "Trap" Grade had selected imported walnut stock and forearm. The C "Trap" Grade, with a straight grip and more trap-like dimensions. The B and C were the same price in the 1930s, as they had been in 1906 for the Remington Autoloading Shotgun, the C just having the straight grip stock of trap dimensions. No Remington price list or catalog I've seen pictures The Sportsman C "Trap" Grade. The sellers pictures are pretty poor --
S502335 01 Sportsman C-Grade.png
From the 1933 Remington Retail Price List --
The Sportsman, 1933 Price List.jpeg