This information is from Nancy Johnson-Strebo's book Featherweight 221 The Perfect Portable. Beginning in the mid 1950s Featherweights were supplied by Type Three black cases. Two kinds of black plastic handles were used. One type is smooth and the other type has a raised ridge in the center. So I am going to assume that if your grandmother's Featherweight had a case with a leather handle then it possible it predates 1950 and she may have purchased it used. If you want to know all there is to know about a Featherweight consider purchasing the book. I refer to mine all the time. The book even contains a reprint of the Singer 221 manual.