Who said anything about non-fragmenting rounds? One can actually see the rounds bursting in the air. Clearly they were fragmenting. What's more, many people kept fragments as mementos. They were all over the city the next morning.
I'm not arguing against flak being used, it clearly was, I'm just wondering if other rounds were used too, given that AA at the time included... well... some big bullets if you want to put it that way (which I do).
A dirct hit with either should have destroyed ANY balloon, but flak at least has a chance of bursting well off target if the altitude is at all off. Still... it is very odd... it's the only reason I'm reaching for, 'multiple balloons, suspended high above the body caught in searchlights and flashes.'
It could have been a really clever drill, but I admitted before and will again, I doubt we'll evere know. SOMETHING was there, tracked on radar, caught in searchlights, and a hell of a lot of live rounds were expended... it's a mystery to me.