Not as up on the fine AH Fox doubles as others here, but you might also want to use the Forum link to connect with the Fox Collectors Assn- we are fortunate as we have members here that also belong to that fine group of gents who appreciate fine American boxlock doubles--
All I can tell you is that this A grade was made prior to the USA declaring war on Germany after the Lusitania, due to German _U-Boat torpedoes, was sunk taking some 16 USA citizens down to a watery grave- After that the AH Fox Gun Co. was unable to get the fine Krupp Flusstahl (fluid steel barrels) and develop the fine Chromox Steel barrels instead.
There are several time frame patterns also for the difference in engraving styles over the years, both for Parker Bros. and AH Fox guns--