When trying to fly the Mi-48 and use manual fire I can fire of about 2 rounds before the gun "freezes" and I have to wait a few seconds (about 5-10) before firing again. This only happens when connecting to the multiplayer server not when previewing it in the editor.
This is a custom map that I have made that is supposed to be 7v7 chopper battle. you can connect to the server and try it out at: 68.232.160.194:2302