The gatling laser uses actually two sounds, one from Fallout 1 (this one is cool) and one from Fallout 3 (not as cool).
The Fallout 3 gatling sound suggest something less powerfull, so the idee is:
-make gatling use only F1 sound
-keep the F3's for the future laser smg
So both weapons will have their own sound that fits with the size of the gun.