Ed, the answer to your question is already within this Thread... if you had been paying attention.
Krupp was a large integrated steel maker. They were not a barrel maker. Over the years, barrel makers who wanted to build barrels out of high quality steel chose names like Krupp, Bohler, Whitworth, etc. When they ordered their steel, they could choose from various grades of steel with different analysis, composition, and machining qualities.
When they completed their barrel, they could justifiably stamp it with the name of the steel it contained. But Krupp steel barrels produced by one barrel maker could be quite different than Krupp barrels produced by another barrel maker. They were likely similar, because barrel makers and gun manufacturers desire similar qualities of strength, machinability, corrosion resistance, etc. But without testing them all, there is no way to know.
This is why sending out one or two samples for metallurgical analysis really tells us nothing but vague generalities. And even the steel purchased by the same barrel make at a different point in time could have a different composition. You would have to have access to every purchase order for barrel steel from every barrel maker to know exactly what grade of Krupp steel they used.
Just remember, pure elemental gold or pure elemental iron will always be gold or iron. But steel is a generic term for an alloy, with literally thousands of different formulations. As such, no two heats will ever be perfectly identical in analysis or composition, under normal modern methods of steel manufacturing. Final analysis was even less precise a hundred years ago. But I could probably impress the hell out of you with a bunch of copy-and-paste pictures, advertisements, and random analysis.
