technically all mccree would need to do is try hiding and stalling for time, probably as all might fought other people, before High Nooning him right at the time limit
and hope Deku isn't around to foil his plans with a good kick in the face
i dont think mccree has the maneuverability to hide from all might plus as soon as he high noons all all might has to do is rush him, he can't fire faster than he moves and he announces the attack so preemptively