I just made a sample for your info:
It has more of a "pew pew pew" sound rather than the Tac-HUD from the cartel market and it also doesn't have the lame holo-sight from the Tac-HUD, which for me is great since that holo-sight is completely dumb there.
I myself prefer the X-52.
yah can't stand the darn "hud" rifles either.
Had a slight hope the x-52 (which is pretty much the same "gun" minus the lights) would retain the sound. It does look like an M-95 too.
Tough luck. Actually like the sound better on custom-built. more tac-tac and less pew-pew (really no idea how to say that otherwise xD)
The X-52 is still the probably best looking rifle out there. If I stumble upon one I'll switch, but I don't like it 300k better than the custom-built one :P