Accepted terminology when these barrels were being made was that "Damascus Twist" was twisted in the bar before wrapping, "Plain Twist" was not.
Neither was made from a Solid Bar. Damascus could be made from a single twisted bar, but was most often of two or more joined together after twisting prior to wrapping.
The Plain twist bar consisted of layers of iron or iron & steel layered together then formed into a flat bar which was then wrapped edgewise around the mandrel.
Problem today is much of this original terminology is unknown to many & the terms are often used incorrectly, causing confusion.
Stub Twist & Stub Damascus was also often used in the early days of barrel making. These originated from using pulled horseshoe nail stubs mixed with chopped pieces of coach springs which were brought to a welding heat then hammered together. This was then rolled into a bar which was wrapped for Stub Twist, or first twisted & then wrapped for Stub Damascus.
Essentially the bottom line is if a simple spiral pattern shows it is Twist, if there is a pattern then its Damascus.
I would agree with you, the barrels in question here are Twist, not Damascus.
