Not sure about this one, but i think you are overrun the RPC buffer.
You also transmit a TraceHitInfo struct, who is heavy.
Try to transmit thing who are smaller (like origin of the shoot and direction, so you can just trace hit on you’r client, to avoid sending the whole struct).
Also, are RPC you send reliable ?
Must be the point here.
For a good practice, you probably want to send Client to Server RPC (Server, Reliable) when you shoot, and to replicate the shoot for the client, use RepNotify (see how they do on ue4 FPS Project)