Sporting Life reported the guns, hulls & powder used by competitors in major shoots 1895-1902. It is clear that prior to mid-1895 the choice of the "top guns" was British, thereafter a Smith, and starting with the 1898 GAH (mostly) a Parker. The great Fred Gilbert left Hunter Arms for Parker after the 1899 GAH.
https://docs.google.com/a/damascuskn...FKEyuY/preview
AND most of the American team in the 1901 Anglo-American Match were induced to use Parkers
https://docs.google.com/a/damascuskn...jEdR4j_E9l4HLw
It may be that Parker, by advertising and price, was perceived as the 'high class' gun, and there were only so many 'high class' buyers out there.
It is interesting how popular the "The Yankee Sidelock" was in the South, esp. 16g guns, as were Lefevers among the 'well heeled sportsmen'.