Well.. I can only help with C++, but I believe that in c# it is done the same way. Run First person shooter template and see how crytek did this. In shortcut they spawn the bullet entity in the place of Player's bone attachment (which is located in front of the gun) and then add impulse to that. I have absolutely no experience in c#, but in C++ it was done this way.
Cryengine tutorial videos on my Youtube channel! Check it out !