Someone somewhere helped us get to a point where 34" inches is the common shooting length for trap guns. That person(s) I am sure is smarter than me. If 34 is the right length and we put on a fiber optic sight that sits back 2+ inches then dont we need to do some re-engineering? Or if we want a 34 sight plane should we be ordering a 36" barrel?
There is nothing written or a rule, or even a law that says that 34" barrels are the common length for trap or any others guns for that matter ... What ever works for you would be your normal if you are comfortable with it ... Do not over think the game or try to re engineer anything until you try it and see if it works, proceed from there ... Placement of any sight be it fiber optic or a diamond is personal choice and you will get used to it ... Look at the targets, forget looking at the sights and worrying about where they are ... If you try, you can make it lot harder than it already is ... If your concerned, remove the old sight and put the fiber optic sight right over where it was, no more problem ... WPT ... (YAC) ...