It was the Payne-Aldrich Tarif Act of 1909. Very interesting reading. Government wanted to tax domestically made barrels. The gun makers testified that it was much cheaper to import tubes from Belgium. Walter King testified that Parker made their own barrels (Laminated and TWIST) from 1877-80, but gave it up as too expensive.
Here is a link to a very good and thorough discussion on the matter on Drew Hause’s Damascus Knowlege site:
https://docs.google.com/document/d/1...S6OIN1bA/edit#