From my research, which is still ongoing, there were several Model 21's made in .405. Elmer Keith, in his Shotgun book, refers to a small number being made in the 1930's and I have found two more that were made around 2008. The newer Model 21's were made by the Connecticut Shotgun Company, for Winchester, and one was engraved with American big game animals in gold (The Grand American pattern) and the other was engraved with African game animals (The Grand African pattern). There is no telling if any others were made although, without a doubt, the number would be very small.