Well, early on all the tube makers were frightened so they sent the individual tubes in for a failure test as they were fully responsible for the whole lot. After the initial hurdles were overcome, the tube makers would send joined tubes and finally the makers would submit an longarm in the final state. Confidence in the steel components, which were instep w/ the powder development, was high.

The numbers are just for the joining process. Is the tube steel Krupp?

Cheers,

Raimey
rse