Why? the CSAT already has their caseless bullup 6.5 TAVOR-replica

Why the CSAT have weapons and vehicle Russian?
Why not add more?

Now thats in my opinion a senseless ticket... Man, use your imagination, over 100 different Weaponmods are available for download...

CSAT is mainly Iranian

just a small part of their equipment is actually russian, why not add more? because in a real life scenario the CSAT would not need them, why not to give the US army an M16 just because it looks and works great nowdays? because in the game they are useless, the same can be said of modern guns.

5.56 mm with a cut-off of three by 6.5 mm with great shaking of rifles significantly it? AEK may be not only at CSAT.

CSAT consists of Iran, China and Russia. Only Iran is the apparent force in the current story line and map available. With Expansion, we could possibly see Chinease/Russians in. However, The weapons you suggest... First off the Katiba is not a Tavor replica. The Katiba's real name is KH-2002, which is a Rifle i believe is being made in Iran. It could possible have Chinease help for manufacturing as well. AK-12 would seem like it would be more fitting of the current era in Arma 3.

This Chinese fake m16 modified Iranians. It would be better armed Iranians A-91M than Chinese knockoffs.
AK-12 rifle bad that has not passed the battle-test last fall 2013. June 22, 2014 there were new тest that completed AK-12 passed well.

The Armaverse timeline does not necessarily reflect the development of real-life weapons and armory. In ArmA 2, we saw the SCAR-L and SCAR-H become commonplace US Army weapons for Operation Arrowhead, which we know in real life to be false - the US Army still uses the M4A1.

Similarly, in ArmA 3 the new standard for conventional warfare is 6.5x39mm Grendel. This is presumably because body armor has developed to the point where 5.56x45mm and 5.45x39mm are no longer sufficient. Besides, the CSAT known on Altis are Iranian soldiers, not Russians.

EDIT: US Army actually uses the standard M4 carbine.

*actually, the US army uses the standar M4, not the M4A1