Pre war gibson mastertone banjo dating
The RB-75 (Crowe) had the flying eagle pattern, the RB-4 had the flying eagle pattern, the Earl Scruggs Model had hearts and flowers (also had an ebony fret board).
This means that these banjos were made prior to 1947.
This was also the beginning of the Bowtie banjos, which lasted until 1969, but with a peg head change in 1968.
The Bowtie banjos were available in arch top or flat head, and some of the flat head tone rings had 20 holes and some had 19 holes.
Here are some more pics: The Gibson Mastertones of the 1950's were constructed with about the same specifications and quality levels of the 1930's and 1940's.
Unfortunately, they discontinued the Flat Head Tone Ring by the end of the 40's.