You simply cannot use the word never or always in a discussion of Lefevers. However, one of the 2 known Uncle Dan grade guns (the 12 gauge) has Whitworth Barrels. The 16 gauge has Krupp. I am not aware of an Optimus grade Lefever Arms Co. with Krupp barrels, although that doesn't mean there aren't any. All I have seen with fluid steel barrels were Whitworth although Kilby barrels were offered in 1892.
The point being is that the story I originally quoted doesn't make a lot of sense when it states that the Krupp barrels were thought to be superior to Whitworth for bargaining purposes.

Great-Great Grandson of D.M. Lefever
www.lefevercollectors.com