Depends on the chanter design, as has been noted on this forum before. Ask the maker for details if you are in doubt as to whether you can span it. I know of a published B design[1], at least, with a right-hand span no wider than many concert pitch chanters. On the other hand, Joe's right, some Bflats and even C's can be real tendon-stretchers[2]; my point being that you shouldn't let the hand stretch issue scare you away from flat chanters altogether.Joseph E. Smith wrote:...ut from D to Bb, well, it'll take a bit of getting used to... especially if your hands are on the smallish side.
[1] - the SRS 'possible John Coyne chanter' described by John Hughes. Can't recall if it's v1 or v2. Coyne C and C# are almost the same in bottom-hand width, at most 1.5mm narrower. This apparent ergonomic focus is one of the things that impresses me about Coyne.
[2] - Kiernan Bflats, for instance, can be pretty wide.