Bigragu --=--
I had assembled a spread sheet with all Wildcat 'O'-Rings for a 25 caliber, but you can swap out the rings for the 30 caliber (barrel, for instance) as I believe all of the other rings are the same.
https://www.airgunnation.com/topic/fx-wildcat-gen-i-25-caliber-o-ring-spreadsheet/
