western electric 315H wooden ringer box question

[southernphoneman]

can anyone tell me what year this western electric model 315H ringer box would have been made?

[Sargeguy]

Is there a wiring schematic inside the front door?  Sometimes they will have a date at the top.  It will give you a starting point.  I would give this one a date of 1920 give or take 5 years.

[poplar1]

The 1908 catalog #2 shows a 315A, which has the hinges on the right.

315Hs with hinges on the left and black gongs are shown in WE catalogs until at least 1939 (#10). Also shown in #5 (early 1920s; shows dial desk stands), #6, #7 (1929), #9 (1935).

What year did they start painting gongs and trim black instead of nickel plating them?