Judge, I suppose it is possible for something of this nature to develop in a modern steel barrel. But, as I see it, is highly unlikely unless the steel is very poor quality or a portion of the wall has become exceedingly thin for whatever reason.
Demonwolf, the test can indicate a straight through defect. A more pronounced bleed of the penetrant indicates a more severe defect. The thin red line in the photo above indicates a surface flaw but if you look at the barrel/rib seam just above it there is considerable bleed of the penetrant. This indicates a void in the solder joint.
It's interesting you mention barrels passing proof which may otherwise have a defect somewhere. While doing research I recall reading one of the early makers, I've forgotten which one, actually tested barrels using pressurized water before sending them off to proof. I'll look that up to relearn who practiced this process.
Lining the barrels is out of the question and no way will this barrel set be used as is. It's conditions such as this that gives Damascus barrels a bad reputation. That barrel is compromised and I shudder to think the potential, even with a black powder load. It's a disaster just waiting to happen in my opinion. We'll separate the barrels, scrap the one with the crack and save the other for a single barrel fowler project.
Yes, we are in the process of developing modern steel barrels to replicate the original form of the early sporting barrels. Setting the barrels into the stock will be much simpler and the barrels will be more historically accurate in appearance. As for the faux Damascus pattern, I know of only one person here in the states who has mastered this process. Will he divulge his secrets? I haven't the nerve to ask. In the meantime we'll continue to experiment and hopefully arrive at the "perfect solution".
Hank
