The setminmax() function is not networkable thus your behaiviour is to be expected.

What you see on the client is the fat or narrow hull definition for the model. This is the same as you would see on the server before the setminmax() call.

You would have to make a setminmax() call on the client following entity creation. Then similar models will have similar BBs.

Since you are creating the entity on the server, there is no automatic way of setting this for te client. The two best ways to do this are to have a skill trigger event_receive and that starts setminmax() (with me already set since it's in the entities event function; my prefered method) or by using proc_clients to start the setminmax() function on the client (a bit harder since the function would have to determine the pointer to the target entity).