Desert Zaku's two machine gun variants

[False Prophet]

So the Desert Zaku is equipped with either one of two variants of the 120mm Zaku machine gun: either a compact model with a lot of things removed (this), or one with a different stock and longer barrel with barrel jacket (this). Could anyone figure out what the second variant is supposed to do? It gives me anti-air vibe, but doesn't the Zaku machine gun have specialized anti-air rounds that it load from the box magazines?

And while we are at it, how many variants of the 120mm Zaku machine gun are there?

[MythSearcher]

So the Desert Zaku is equipped with either one of two variants of the 120mm Zaku machine gun: either a compact model with a lot of things removed (this), or one with a different stock and longer barrel with barrel jacket (this). Could anyone figure out what the second variant is supposed to do? It gives me anti-air vibe, but doesn't the Zaku machine gun have specialized anti-air rounds that it load from the box magazines?

And while we are at it, how many variants of the 120mm Zaku machine gun are there?

I recall an earlier thread talking about the anti-air clip for the Zaku machine gun.
viewtopic.php?f=17&t=18129


But the nice Japanese wikipedia listed the difference models:
https://ja.wikipedia.org/wiki/%E3%82%B6 ... C%E3%83%B3
As well as the Japanese Gundam wikiw:
https://gundam.wiki.cre.jp/wiki/%E3%82% ... C%E3%83%B3
So you get 3 main types: M-120A, ZMP-50 and MMP-78, with their own variants.
M-120A1 is the most basic type, AC is one fitted with a heat blade and AS is the desert variant(with flash hider and removed hand guard, also fitted with scope. This variant also has a long barrel variant)
ZMP-50D is the Zaku I ZMP-47D(105mm) successor. The drum magazine is offset to the side.(originally designed for the MG model because the regular drum position interfered with the chest, but later MG versions fixed it and thus returned the centre drum position)
MMP-78 is the one that can use the anti-air magazine.(earlier sources states that this model has an early type and late type) A grenade launcher is added. /WG variant means Wide Grip and is designed for Dom's larger hands.
MMP-80 (The 0080 06FZ machine gun) currently is supposed to be 90mm, but earlier model specs stated 120mm as well.

[False Prophet]

I recall an earlier thread talking about the anti-air clip for the Zaku machine gun.
viewtopic.php?f=17&t=18129


But the nice Japanese wikipedia listed the difference models:
https://ja.wikipedia.org/wiki/%E3%82%B6 ... C%E3%83%B3
As well as the Japanese Gundam wikiw:
https://gundam.wiki.cre.jp/wiki/%E3%82% ... C%E3%83%B3
So you get 3 main types: M-120A, ZMP-50 and MMP-78, with their own variants.
M-120A1 is the most basic type, AC is one fitted with a heat blade and AS is the desert variant(with flash hider and removed hand guard, also fitted with scope. This variant also has a long barrel variant)
ZMP-50D is the Zaku I ZMP-47D(105mm) successor. The drum magazine is offset to the side.(originally designed for the MG model because the regular drum position interfered with the chest, but later MG versions fixed it and thus returned the centre drum position)
MMP-78 is the one that can use the anti-air magazine.(earlier sources states that this model has an early type and late type) A grenade launcher is added. /WG variant means Wide Grip and is designed for Dom's larger hands.
MMP-80 (The 0080 06FZ machine gun) currently is supposed to be 90mm, but earlier model specs stated 120mm as well.

Found another threat talking about this topic: https://www.mechatalk.net/viewtopic.php?t=15769

I think Zeonic Translation posted something on Twitter about one or two companies which specialized in developing these guns during the OYW. I should probably ask him.