There are a few smiths with experience doing Penetrant Dye Testing; Rocky Hays is one. The problem again is in the interpretation of the findings, and inability to identify flaws/defects/inclusions
within the barrel wall
The metallurgical engineer and NDT supervisor at TEAM Industrial Services with whom I worked thought radiology would be a better test
I'm glad we're discussing this again, and hope someone might decide testing pattern welded barrels (short of proof testing) could be commercially viable