[Swordmaker]

Maybe it was someones custom "cut" shell or some other baloney and only a partial ignition due to moisture.

The photo shows a standard, unmodified iPhone 5C case. Shot shells are designed to handle moist and even wet conditions in a duck blind. Modern smokeless powders, unlike black powder, actually burn rapidly and impart the vast majority of their impetus in the first 12-18 inches of barrel length.

[FunkyZero]

i’m somewhat familiar with shotshells. Although i never counted, I’ve probably reloaded in excess of 10,000 of them and shot at least as many in the past 40 years