I was a Battery Executive Officer for 4 years and a Commander for 3.
She was no in front the of the gun, but off to the side where you catch a lot of the muzzle blast.
While not the best place to be when firing, you can get some great pictures from the vantage point.
Correct... It is obvious from the video that it was the blast from the brake that knocked her over.
Having been on the firing line with .50 BMG and 20mm... I do enjoy that “thump”. Even then, I can only imagine being that close to a field piece like that when it’s touched off.
As we say up here in communist occupied Minnesota, “Oof-dah.”