Making a combat game with ranged weapons? FastCast may be the module for you!

When receiving a remote event from a client to server, the first parameter on server is the player that fired it, So for Example

in a local script

Local RemoteEvent = -- to the remote event

RemoteEvent:FireServer() -- add some parameters to your likings

in a server

Local RemoteEvent = -- to the remote event

RemoteEvent.OnServerEvent:Connect(function(Player)
--do the fast cast here
End)

I believe this is the solution you wanted?