Interesting. Some spiked, some not so. Kind regards, always, Jim. P.S. Yes, we have no bananas, we have no bananas today!
I think some of the ones with failures along the axis of the bore are from barrel obstructions. I've seen two of them and I don't do a lot of shooting. One was a 6.5mm Mauser with snow in the barrel and one was from a faulty hand loaded cartridge that had either a low powder charge or no powder at all. The primer pushed the bullet from the previous cartridge into bore and the shooter didn't notice and fired the follow up shot. I can't remember the caliber but I think it was a .30-30. Plugging long tank barrels coming down steep hills was a design concern. That's why the early M3 Lees have the shortened barrel with counterweight.
A problem that had been encountered as early as 1917 with the British Mk I and Mk II male tanks resulting in the MK IV and V having shortened guns. A particular problem for sponson mounted guns it seems