Pro: Gunsmith gets more paid work.

Con: You have less money after he does work.

Really, I NEVER have the forcing cones lenghtened on my old guns. I will polish them if rough (common situation for cheaper guns) -- that really does make difference in evenness of patterns. I do have one that previous owner lengthened forcing cones. Does not shoot any more even patterns than those with short cones from early 1900s.

Niklas