Thanks for the clarification Researcher. I've got 1924 for the 3" here
http://www.picturetrail.com/sfx/album/view/17318961

1923 Hunter-Trader-Trapper introducing the Smith LRWF; mentions 3"chamber



1924 now "special 3-inch shell"



1925 letter claiming loss of pattern % with the 2 3/4" Super-X in the 3" chamber