what do you mean by "hitting"?
are they bullying and inkuring the cories or just getting them out of the way? Fish will have a pecking order and the bullies will take what they want and the weaker fish will move out of the way. There usually won't be a problem because the weaker fish don't offer resistance and just leave.
Issues will arrive when you have two stubborn fish that will fight like my oscar and pleco. They've calmed down now but they would give quite a show. My pleco rammed the oscar in the aquarium cover hard enough to stun him and make a huge splash and water spill. they've now calmed down. The pleco is much tamer since the oscar give him a small bite.
I doubt cories and loaches will go that far though