Not just to shoot and reload - but to do it in full body armor, in the dark, in a closed area saturated with tear gas, while masked!
Ask anyone with military training if this is an operation a first time gun shooter just up and does, managing to shoot 71 targets in the dark, with no training or range practice, with no dry run, based on reading directions from the manual or paying a video game
I agree, Silverleaf. The killer was smart, obviously, but we can safely assume that kind of assault requires a lot of training and practice. Combine that with the extreme cost of the firearms, ammunition, armor, etc., this appears at first glance to be a very well-funded and well-planned paramilitary operation. I can’t imagine he was acting alone in this horrible massacre.
That said, it does appear someone or a group of someones did pool their money and come up with a plan.