Re: flutting a 20" barrel
Well you can flute any contour barrel, my Steyer Scouts are prime examples of pencil thin 19 inch barrels with six flutes that shoot sub MOA consistently.
That being said I agree with what was said, and believe for the average barrel/smith there may be ill effects 1) let the barrel maker do it 2) if done improperly it will effect harmonics 3) on a 20 inch barrel its not going to save much weight unless a "bull" barrel.
On my "ultralight" pack guns I have used chrome Molly and chose not to flute for weight.
Bottom line if this was negotiated for and part of the agreement you should have received it or at least a call to discuss the problems not the surprise. I am not desegregating all smiths by any means but have found many notorious for doing what they want or is easy and not the customer. Bottom line when you find a great one that pays attention to detail stick with him. I get everything written down for there sake as much as yours.