All the research in recent years around maker's marks points to the fact that it has always gone on.

Damascus barrels coming out of different makers purchased from the same rolling mill.

Percussion guns show up with the locks engraved "Josh Golcher". In fact that is Joseph Golcher who never left England. His brother James was most likely selling those locks to American makers.

I see Meriden hammer guns with 2 different receiver forgings. An obvious signal they had a supplier. The list goes on.

Get Raimey started about Krupp and the probability they were licensing steel recipes. grin

Pete