From your description I can roughly identify that you either have the Iver Johnson 22 Supershot Sealed Eight FIRST or SECOND edition (the third edition was not marked 22 Supershot Sealed Eight on the left side of the barrel and the barrel sides are flat)
Big range for you here, the first series ran from 1932 – 1941 The second ran from 1946 – 1954
You should be able to find a model number, either 88, 833, or 834. If the model is 844 then you have a third series. If the grips have anything on them referring to High Hold it is the first series, pre WWII First series have an adjustable finger rest. Hope this helps, if you think of anything else that might help with positive identification please send it in.