Certainly in the MH60, the same minigun weapon in different turrets has different names. One is class "M134" and the other is "M134_2" (can't remember which is right and which is left, but I'm sure you can find that out).
In third-party vehicles however, modders may not have shown the same forethought though.
EDIT: bear in mind that with you system, you do damage with a created object (which doesn't affect AI correctly and doesn't blame the original firer for the shot in event handlers). You ideally should have the gun fire the "live" ammo, move that away somewhere safe, replace with created "dummy" ammo, then replace the dummy with the live ammo after the set time. This way, any damage that the weapon does is correctly attributed.