I came across this article some time ago and found it intersting reading.
http://bellsouthpwp.com/r/d/rdevelli/Gibson%20F-4.htm
I (am so lucky as to) own a 1917 F-2 and a 1921 F-4, and this article gave me some insight to the development of the mandolins of that time frame, it also provides some information on the influence of Lloyd Loar and Lew Williams on the design and quality of Gibson mandolins.
You might find this interesting reading and perhaps others with knowledge of Gibson from that time period can add to this.
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