It's possible to build a single-barrel or dual-barrel remodel that can be applied to both standard tank and dual-barrel tank 
while still showing the correct firing sound and particle effects.

The following conditions must be met:
1. The node structure contains nodes necessary for a standard tank gun.
   That means a minimum of [Gun, G, HP_gunFire]
   HP_gunFire should be placed at left muzzle.
2. The node structure contains nodes necessary for a dual-barrel tank gun.
   That means a minimum of [Gun, G, G_L, G_R, HP_gunFire_L, HP_gunFireR ]
3. In the corresponding UMLprofile, <supportDualGun> is set to true under <gun> node.
   for example:
  
     scripts/client/mods/UMLprofiles/EFGF_M61A5.xml:

<root>
	<models>
		<EFGF_M61A5>
			...
			<chassis>  ...  </chassis>
			<hull>  ...  </hull>
			<turret>  ...  </turret>
			<gun>
				<supportDualGun> true </supportDualGun>
				<undamaged>vehicles/terryzxc/EFGF_M61A5/normal/lod0/Gun_02.model</undamaged>
				...
			</gun>
			...
		</EFGF_M61A5>
	</models>
</root>

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If your remodel has two barrel, it should end up with a hierachy similar to this: (recoil animation bond to G_L and G_R)
                                /  HP_gunFire
                           G_L --- HP_gunFire_L
                        /
nodes_01 --- Gun --- G 
                        \
                           G_R --- HP_gunFire_R

-------------------------------------------------------------------------------------------------------------
If your remodel has single barrel, it should end up with a hierachy similar to this: (recoil animation bond to G)
nodes_01 --- Gun --- G_L --- G_R --- G --- HP_gunFire 
                                       \
                                           HP_gunFire_L
                                       \
                                           HP_gunFire_R
-------------------------------------------------------------------------------------------------------------
[about sound and particle effects]

when a single-barrel tank invokes a dual-barrel stock/mod remodel, it will always play salvo effect(firing two gun simultaneously).
    [*] sound and particle is designated normally using <effects> node under <gun> in a UMLprofile, or the override node <effectsGun> found in ownModel.xml
    [*] it only accepts effects built for single-barrel tank, ie the usual shot_main, shot_large, shot_huge, etc..
    [*] it will NOT accept effects specifically built for dual-barrel tank, like shot_dualgun_large_L, shot_dualgun_large_R. 
        Using such effect will have unforeseeable consequences. 
    [*] if no specific sound effect was given, the stock default firing effect will be played simultaneously at both HP_gunFire_L and HP_gunFire_R


when a dual-barrel tank invokes a dual-barrel stock/mod remodel, it will play the corresponding effect according to how player fires the gun.
    [*] not possible to designate a different sound/particle effect. it will always play the stock effect from the actual in-game tank.
    [*] you may still define <effects> node under <gun> in a UMLprofile, or the override node <effectsGun> found in ownModel.xml, 
        but these will take effect only when this profile is used by a normal single-barrel in-game tank.

when a dual-barrel tank invokes a single-barrel stock/mod remodel, it will always play the single-barrel firing effect no matter how you fire the gun.