WOW MARK!! THIS CHANGES EVERYTHING and to my knowledge is the first (likely-more later) American produced CROLLE pattern barrel! (And was well worth getting back from Guatemala

) Sure glad that book hasn't been written yet.
As PeteM said, courtesy of EDM
Letters in
The American Field in 1878 state that a barrel forger named John Blaze of Birmingham, England had immigrated to America to make Wesson's barrels. He was listed in the 1865 Worchester, Mass. City Directory as a 'Gunsmith', and 1878-1881 as a 'Blacksmith.' Whether he left Wesson for Parker's employ after Dan Wesson shut down his shotgun production in December 1870 is uncertain. Other Wesson gunmakers did take jobs with Parker, including Charles A. King. Daniel Wesson is reported to have ordered 400 sets of barrels from a Belgian source, some of which had "Wesson" spelled out in the damascus pattern. Only 229 guns were made according to existing factory records; the fate of the remaining barrels is unknown.
c. 1870 Wesson with
Laminated Steel
This also from EDMs research:
c. 1870, Parker offered ‘Plain Finish-Iron’ Barrel for $50, ‘Superior Finish-Iron’ Barrel for $75, and ‘Laminated Steel’ barrel for $100. The Parker-made 'Laminated' barrels carried a special 'PB' mark. Some 1870s Parker Hammer Lifter guns are marked "Twist" on the rib, but are clearly laminated steel.
T1 Lifter with 'PB' in a shield, 'T' for Twist, and an unknown mark covered by the bottom rib.
Parker Brothers' advertisments in late 1870s pulp weeklies claimed "This company has succeeded in making their own steel barrels..."
Letters in the Nov. 1878
The Chicago Field from Parker Brothers included statments that "We import largely both Laminated and Damascus, and
also manufacture a very fine Laminated--as fine, we think, as any we have ever seen imported. We have made them about eighteen months."
The Chicago Field on March 8, 1879 reported "The Parker Bros., of Meriden, Conn., commenced making
twisted barrels in the Spring of 1877."
Those barrels are a poor aesthetic effort at 3 Iron "Turkish", and by 1870 both the English and Belgians were making very nice barrels SO my opinion (which is worth nothing definitively) is that those were made in the US.
More later when my brain starts working again