Yep; Obstruction burst, fit all the signs including location. Remember that no two bursts are identical. One looks at the signs, but do not expect to find an exact Twin which looks just like the burst in question.
As I mentioned in an earlier post the barrel may well have been struck a bit thinner on the outside than between the barrels, obvious if more was done after assembly. The pressure may have peaked Just high enough to stress this thinner area & the stiffening of the top rib would well explain it not being bent. Had the obstruction been heavier the pressure may have risen a bit faster & bent the rib. Remember also when the load hits a "Movable" obstruction the burst will normally be a bit forward of where the actual obstruction was located.
I am sure the Gentleman who did this learned his lesson well. No Criticism from me. Do thank him for sharing with us as to what actually occurred & allowing the pictures to be posted. We all should have learned a lot from this thread.
