Try geting a screw driver then reseting the pistons with it then just go ride and the pistons will adjust then selves to a good postition so they don't rub (hopefully). This might sort out your problem or it might not. It's worth a try though .
All the 4 bolt mounts are the same size because they all have to fit maguras. On all the maguras the pistons are the same size. Why are you posting in NMC?