32.5 yards with the Winchester 20 gauge 1 oz. bismuth load.

Bismuth, on its face, offers several potential advantages over steel: better density and no more peril to shotgun barrels than lead, safe for old fixed choke 'lead only' barrels. Thirty years ago, bismuth shotshell potential captured the imagination of renowned ballistician Edward Lowry. His article is required reading; Lowry. 

Back then, bismuth was not legal for waterfowl hunting, and faced some two million dollars of investment to go through the government approval process. Bismuth faced manufacturing hurdles and had the problems of erratic shot sizes, along with brittleness problems and resultant fracturing. Bismuth shotshell companies launched soon failed.

Finally, it appears that Winchester has cracked the code, offering buffered bismuth loads with pressure cast shot that is uniform in size and shape. It is then polished and tin-plated. The shot does not fracture in the barrel and the patterns are impressive. It runs in the area of two dollars a shell, less than half of tungsten-based loads.

Above, 50 yards with the Winchester Bismuth 12 gauge load.