Someone apparently figured out how to cut chokes in pattern welded tubes > 150 years ago
W.W. Greener produced new shotguns with damascus barrels in 2007-2008.
From the Greener website in 2007:
“Barrels - are made of the highest quality steel and bored to maintain the famous choke boring improvements, made by W W Greener in the 1870s, to optimise shooting performance, and to ensure patterns of shot guaranteed to meet customers' exact requirements whether for game, wildfowl or clay pigeon shooting. A few pairs of guns are being made with interchangeable steel and Damascus barrels.”
Vic Venters (Dec. 2008) wrote an article in the Sept/Oct '07 issue of Shooting Sportsman regarding the Greener guns:
“They are indeed newly made damascus barrels, built on vintage tubes that David Dryhurst - Greener's master gunmaker - has been collecting since the '60s and '70s. Some are old Greener stock, some are English and no doubt some are Belgian. A few of these sets came from Dyson..."
Vic shared that Dryhurst told him that cutting choke in crolle tubes was more difficult in that the metal would occasionally fracture.
Pattern welded tubes, related to the high heat hammer forging process behave as a monometal.
It would have been valuable to prepare photomicrographs of the micro-fractures to see if they occurred at the iron-steel
alternee welds.