Jim,
Consider the following: Why the heck would any gunmaker "guarantee" a gun built from barrels of unknown origin, regardless of whether they were damascus or chromoly steel?

Take a set of Krupp tubes into H&H and ask them to build a gun and guarantee it. They'll show you the door, I'm sure. There's just no reason for anyone to guarantee something unknown by a gunmaker. And you telling them they are the finest Krupp steel isn't good enough any more than a metal saleman saying the metal supplied for a 747 is good.