As an interesting side note, shortly after the turn of the century, Whitworth decided that they would like to make more money on their barrels. So they started to reduce the shipment size to their main customer, LC Smith. After LC got very short on barrels, Whitworth announced a price increase. LC had started looking around and Krupp sent them some fine (better than Whitworth) barrels at a cheaper price. LC used this lever to REDUCE the price they had been paying Whitworth instead of paying more. They continued to use Krupp as an option.
I was under the impression that Whitworth barrels were considered superior to Krupp. At least Lefever used Whitworth barrels on the very highest grade guns like the Optimus while Krupp barrels were frequently found on lower grade guns in the B&C range. This may have been in a time period before the era you are referring to.
