unity raycast layers in Multiplayer

Hey,

I made an FPS and I currently transform it to multiplayer. Now i have a problem. My Raycasts from my MachineGuns, Pistol,... ignore the layer of the playerprefab. Because of that you can't shoot another player in multiplayer. The Raycast just goes right through him. How can I change it so that the raycast ignores your own player but not the other one. Is there a way of doing it witout different player prefabs and multiple player-layers. And if there isn't how can i use it exactly in my case. Some kind of example script would be much appreciated.

Thanks.