I think this is probably correct. There are people who shoot thousands of rounds per year and there hasn’t been any mind of established pattern of brain damage like this (at least to my knowledge).

It’s possible small arms fire doesn’t make big enough shockwaves. To cause the effects. I’d hypothesize it’s the larger blasts… perhaps even a frequency component to it? Blasts from a fast explosive like C4 could do more damage than slower shockwaves like mortar or artillery shots.

Idk. Interesting subject.