The Winchester Model 21 action is of a typical breech loading shotgun, commonly called a break or hinge action. Like all quality double guns, production is time-consuming due to the laborious process of joining the barrels to produce an identical convergence of shot. The Model 21 was Winchester's effort to make a quality side by side shotgun to rival those of high-end makers such as Parker and Fox; financial troubles plagued the gun's development until the Western Cartridge Company purchased Winchester Repeating Arms in 1931. The Model 21 has a considerable collectors following as it is regarded as almost a custom-made shotgun.