Lots of information here regarding American made pattern welded barrels, and those of Parker; mostly courtesy of Brad Bachelder and John Davis.
Dean's Parker made Laminated Steel barrel is also shown
https://docs.google.com/document/d/1...A/edit?tab=t.0
We now have Twist Lifters with 'M', 'M +', and 'M F'
IMHO there is nothing special about the appearance of the Twist pattern to confirm the maker. The Parker made Laminated Steel pattern is unique.