I'm doubtful about the conclusions. If that streak is indeed the visual blur of the grazing bullet, it appears about a foot long. The nominal muzzle velocity of the 0.224 caliber ammunition normally used is ~3000 ft/sec. For a shutter speed of 1/8000 second, the visual smear of the bullet should be only 4.5 inches long. Contrariwise, if the smear is real, the shutter speed could have been only 1/3000 second.

This means also that the photographer must have had some shutter activation system that was triggered by the event. Such triggering would incur a delay in the start and stop of the shutter opening. Otherwise, this photo being a spontaneous accident is hard to credit.