A lot depends on the barrel contour of the origianl gun. It can be done but to be sure of safety be certain it's done by someone reputeable. I prefer Make Orlen but have talked with him for some time. Briley does good work as does Simmons Gun Specialties (??). I believe the latter are in Olatha, KA. Going from 2 3/4 to a 5 inch is likely possible but to 3 1/2 is guite unlikely. Remember the only way to know for certain is to measure.. It requires special tools but with out them the snith is guessing.. a bad descision..