i had a thought about that not long ago

while i don't play mch on my own, I'm of the same opinion that gauss barrel really destroys the look of most guns

so why not use the secondary weapon slot (which is pointless on all jobs except pld in endgame anyway) as a glamour slot for the barrel

just give the mch players some unique designs including an invisible one

shouldn't be too hard to implement, even though the game counts the main weapon for both slots