The frustrating problem, for those of us trying to learn something, is that images get posted of a "blow up" but no one seems willing to measure the wall thicknesses
Thanks to Randy I have contacted the seller of Flues. We'll see.
The sad part is that it's hard enough just to get an accurate barrel length measurement from an internet gun seller. Far fewer people own a micrometer or vernier caliper than people who own (and can actually read) a tape measure. In addition, a regular micrometer or vernier caliper isn't very good for reading the thickness of a concave curved surface anyway, which is why barrel wall thickness tools have a small rounded piece opposite of the dial indicator.
I'm not sure exactly how it relates to shotgun barrel failures, but when newly manufactured smaller diameter steel pipe or seamless steel tubing fails during hydro-testing, virtually all of the failures I've seen are longitudinal splits. Since a gun barrel in normal use is open ended, it seems hoop stress may be a bigger factor than longitudinal stress, even with a light obstruction. The same seems to hold true for the majority of shotgun barrel failures. However, some barrels may have internal defects, or deep visible pitting, or localized exceptionally thin spots that may exhibit failure somewhat differently. It's rare to see any sort of grenade type shrapnel being ejected in a "normal" burst scenario. I'm sure many of us have seen photos of rifle barrels that had multiple longitudinal splits due to barrel obstructions and much higher pressures. About 20 years ago, I had the pleasure of spending nearly two days getting frequent showers of cold river water while working on a Hydro-tester that was over-pressurizing pipes after the wrong program had been inadvertently loaded into the PLC. I got to see more failures in a couple days than the machine operator would normally see in months.
However, those of us who mostly shoot break open doubles have the distinct advantage that we can use our brains and take a quick look for bore obstructions every time we reload. Falling while hunting, and poking our barrels into snow or mud should be a no-brainer time to check the bores, and a blooper should arouse our suspicions of an obstructed bore too. I've told the story of quickly loading my single shot Savage garage gun to shoot a groundhog near my garden. But just as I was about to pull the trigger, something told me I should check the barrel. I backed into the garage and unloaded, and found the barrel was totally plugged with hard mud from a mud dauber wasp nest.
