I'm trying to determine when Best stopped making keys that have a smaller bow than those currently being made. This would be the earlier type that is shorter than a typical 7-pin key, has the word BEST in large letters surrounded by stars on one side, and stars all around the other side with no space for the keyway letter found on the typical Best keys. I have several unused/NOS cores with the smaller keys & would like to get an approximate date when they were made. My guess would be 1950's?