lost of ammo on vehicle mounts Options

[Qurahn]

I have confirmed on different vehicles but my setup I am using is a M-173 (APC).

I have a GE Vindicator Minigun with an weapon modification Additional Clip.
Here I notice it allow me to load a 250 rounds now that I added that Additional Clip option.
I can use 50 round clip or a 250 belt? with it.
I can load a 250 belt twice just fine when I add the Additional Clip when it is a weapon under the street gear > weapons section.

I am trying to use the Ammo bin option to on the vehicle,
When I move the weapon to the weapon mount on the APC, a (Normal, External, Turrent, Remote), it only allows me to 50 clip only.
The reload screen flashes and does not display the reload screen while weapon is mounted.
I can see the reload screen on the street gear > weapons section.

I tried with a GE Vindicator Minigun without an weapon modification Additional Clip also. No Joy.
I even tried to remove the Additional Clip and even the Ammo bin, Nada.
I still see I can load a 250 rounds after removing the items under the street gear > weapons section.

I am out of ideas.

Plus, if it is possible, can we get a unload weapon ammo option too!