In the early 1980s I bought a Specialty 20ga that had 3" chambers and was marked with the same stamp that is seen on the 3" 12ga guns. At the time I suspected that it was phony because it had a Rosewood stock and small B/T forend and the serial # dated it to the early 20s, maybe not?, but who really knows for sure. I tend to agree with Dave that it must have happened. Jim A.