Hon. Tom Marshall won the 1897 and 1899 Grand American Handicap at Live Birds using a Cashmore. The English team members are listed here, but the guns they used are not recordedhttp://www.la84foundation.org/SportsLibrary/SportingLife/1901/VOL_37_NO_15/SL3715020.pdf
My 'inelegant' citation simply states the fact that the best American shooters, who were very likely induced to use Parkers (with the exceptions noted including TWO repeating shotguns - oh the shame!) quite handily defeated the best shooters of England and Scotland who one would assume used the most effective English gun available for that shooting discipline. After the competition was prematurely terminated, J.A.R. Elliott and his Winchester went on to the Continent and made a bit of money in the pigeon rings.
The document on DamascusKnowledge and links to the original reports are interesting reading, especially the responses (excuses) by the English sporting press.
Here is the doc againhttp://docs.google.com/document/pub?id=185YOyQl7GIB9OYLs9Hr3tnMLHqs4rjEdR4j_E9l4HLw