Thank you Raimey. What was the source please?
Interesting that in 1912 Thomas Hunter and Alfred King 'fessed up and said all their tubes came from Belgium.
Bethlehem was indeed making barrels for Winchester.

“Report on Duties on Metals and Manufactures of Metals by United States Congress.” Testimony of Thomas Hunter and W.A. King regarding the Payne-Aldrich and Dingley Tariff Bills, before the Senate Committee on Finance in 1912.

Statement of Mr. Thomas Hunter, of Fulton, N.Y., Representing The Hunter Arms Co. and Others
The Chairman: Will you state the companies you represent, Mr. Hunter?
Mr. Hunter: The Hunter Arms Co., the Baker Gun & Forging Co., Parker Bros. Gun Co., Hopkins & Allen Arms Co., A. H. Fox Gun Co., Lefever Arms Co., H.& D. Folsom Arms Co., Ithaca Gun Co., N. R. Davis & Sons, and Harrington & Richardson Arms Co.
Senator McCumber: Does the American manufacturer use the unfinished importation?
Mr. Hunter: He uses what are designated in the present bill as “gun barrels rough-bored.” That is what we import.
Senator McCumber: To what extent do you use those?
Mr. Hunter: Entirely.
Senator McCumber: You do not manufacture any of them?
Mr. Hunter: No, sir. We have no facilities for making shotgun barrels.
Senator McCumber: Does any other company make them?
Mr. Hunter: There are a few that make them for themselves only. None are made to be sold. We never have been able to buy any in this country.

The Testimony of W.A. King Representing Parker Gun Co.
Mr. King: I can speak only for our own company in so far as wages go. For instance, on the question of barrels, Mr. Hunter informed your committee that some years ago some of the manufacturers of this country attempted to make barrels. We made some barrels: we built an addition to the factory, put in some up-to-date machinery, and brought some men from Belgium to show our blacksmiths how to do it. We had to pay our blacksmiths not less than 32 cents an hour, up to 40 cents, and we gave it up, because the highest wages paid the Belgian blacksmiths for exactly the same grade of barrel are 11 cents per hour. That is what is paid to the highest-priced man employed.
Senator Smoot: In Belgium?
Mr. King: In Belgium: yes, sir. That is where all of our barrels are imported from, with the exception of our very high-grade Whipple steel barrels.
(“Whipple” is very likely a transcription error for Whitworth.)