I mean, technically he has to shoot them roughly around 30-60 times to kill a target…
But being a smart a#$ aside, Bastion is easily counterable by many things in the game.
You know Torbs turret, right? Same HP, unable to move, just like Bastion in turret form. Another thing they have in common is how incredibly fickle they are when they get jumped, even with Ironclad. Even with all that damage, Bastion can’t kill everything. By the time hes done shredding through a Rein barrier, Winston Barrier, or even a Orisa Barrier, they would have done enough damage to him to kill him off.
Bastion can and will never be good unless he gets his own form of self protection that negates damage, enough damage that allows him to dish it out in return. He should never have to rely, scratch that no hero should rely on another to be viable.