Considering that it is quite probably someone could start about 50 feet away in their match...

Bullets can move at 3000 fps. At that range someone would have .0166666666666 seconds to react. Even with augmented reaction times and speed, it would be near impossible for anyone to pose a threat to even a remotely competent gun user. At 250 feet per second you get .2 seconds to react at 50 feet. Even then that is an a challenging threat to deal with.

Adding in the fact that guns require no initial preparation and can expend multiple rounds in fractions of a second, I'm being quite generous here.