There is a widespread misconception concerning flex nibs and Copperplate-style writing.
A nib with the widest possible degree of flexibility can produce spectacular results in writing Ornamental, Spencerian script and, indeed, in personal flex-nibbed writing. These nibs were made to produce wide, swelled strokes. A typical, currently available nib of this type is the Hunt 101 which is capable of producing shaded strokes of 3.5mm width.
It is not widely appreciated that a nib capable of this degree of shading, is not ideal for Copperplate-style writing which attempts to emulate the engraver's burin of the 17th-18th century. It is generally accepted that the finest examples of this style of writing is shown in "The Universal Penman" by George Bickham. He was an engraver as well as a calligrapher and his book shows engraved "enhancement" of the work produced for publication by the English writing masters of the period. Subsequent Copperplate writing is an attempt to copy this beautiful work, with a flexed nib. This is a restrained style of lettering and in this work, there are very few, if any, examples of shaded strokes of more than 1.5mm in width. In the following example, it is apparent that in Copperplate, every straight downstroke is shaded, as closely as possible to the same extent and is consistent in width. This is extremely difficult to control with a very flexible nib and, in fact, a nib with more moderate flexibility such as the Gillott 303 with its maximum opening of about 2mm is better suited to the task.

Although I'm describing dip nibs here, the same principle applies to Fountain pen nibs. If your intention is to write Spencerian script, or a version of your own flex-nibbed writing, then the "wet noodle" very flexible nibs are what is required. If, however, it is your intention to study the early English Roundhand which has become known, by general usage, as Copperplate-style writing, then a pen with a nib similar to the Gillott 303 with its moderate flexing, is your ideal.
caliken
