Join Date: Jun 2006
You are correct. Those bars and colors of the basic "blazon" are always present. The shield shape changed over time with the general practice of the heralds.
The following well-known book shows an earlier shield type that matches the shield shape on the hackbut. The book states that this earlier shape which I call the "coffee cup" was used only from 1470-1525, as I recall on page 72 or nearby.
Author: Ottfried Neubecker
Title: "Heraldry; Sources, Symbols, and Meaning"
Price: US$ 4.06
Book Description: 288 pp., folding plate, hardcover, very good in a very good dust jacket