OldMontana-very interesting- same author I quoted in the "for sale" forum- now this quote from the article states the same info- it reads as if the barrels, cylinders, backstraps were Italian castings, finished in USA- but the frames, center pins, nipples, screws, springs were made in USA parts start to finish. It specifically states one set of parts was Italian cast/finished USA- but the others were made by Ivers Johnson- giving the impression the frames and arbors were not Italian at all.
In this case, the 2nd gen guns would be superior and the guns to buy
from the OP link, scoll down to the 10th paragraph- a deliberate, specific effort was made by Imperato, to avoid the Italian frames, and use made in USA frames by Ivers Johnson I've seen a few vintage Ivers Johnson BP CB guns at recent gun shows, one was a Rogers & Spencer, they appear to be a premium made gun:
http://www.gunsandammomag.com/cs/Satellite/IMO_GA/Story_C/Cap+%26+Ball+Resurrection
"Unlike their first arrangement, Imperato was now responsible for the entire production of Colt black-powder models. "They were all hand-fitted. There was no way to do mass production," explains Imperato. "We had the barrels, cylinders and backstraps cast in Italy (as Forgett had done), but we finished them off in-house.
We made the frames, the center pins, nipples, all of the screws, springs, and built every F Series gun at Iver Johnson Arms. We even used the old style color-case hardening method with the charcoal and bone meal, and Colt's exclusive Colt Blue Finish. They turned out pretty good. In fact, I think our finishes were actually better than Colt's single actions being done in Hartford."