All GMG's firing sounds have been broken for a while, I´m surprised nobody's posted a ticket yet, so here it is.
When firing the GMG, the firing sound cuts out with a very rapid fade about halfway through the sound. The reverb and echoing of the full sound is missing, making the GMG sound very artificial and quite frankly, broken.
Go to external view on any GMG equipped Vehicle, fire the GMG in single shots and bursts, notice how the sound cuts out compared to the reverb and echo that the RCWS .50s have or pretty much all other guns in the game.
Best to be tried on Marid or Panther as they have GMG and HMG, to compare the sound endings directly
As of the most recent patch, this problem persists for me. Does anybody else see this?