Speaking only for myself, I have been researching these two model guns for about 14 years and have purchased 42 of them for my research and collection. As a result of this, I have written two books, the first one printed in August of 2014. The revised edition, printed in May of 2017, was made possible by talking with others who read my book and contacted me with information about their collections of these guns. Others who have shared information on this forum with us, are, I suppose, speaking from their personal knowledge and experience with these guns.