Most (all) Best gunmakers employ Instructors/Gunfitters who would meet with the prospective new buyer at the pattern plate.
There the gunfitter would advise and perhaps educate /change the customer in the correct method of mounting and shooting, with the use of a 'Try-Gun' the customers basic preferred measurements would be arrived at.These dimensions would then be conveyed to the workshop to give the stocker some dimensions to work to.
I believe the purpose of the W.C.Scott chart was to allow the customer to provide a set of dimensions that Scott's could select a stock that was near to the final form and possibly only then required minor alterations.It allowed them the insight as to wether they were stocking for a Giant, Dwarf, stick insect or rotund jolly old chap.
