Question about the acquisition of some PVE guns

DrZaref

Long story short, i came back the previous month after a very long hiatus and i missed a lot of content so i'm kind of trying to catch up in PVE stuff in particular.

What is most effecient way to get these gun?

-Raging bull buster (it's temporary in grim reaper box, is there a perm version of it?)

- Righteous Shotugun (is there another way other than conquerer points from Void/Frozen maps) ?

-AK buster, Seriously where is this gun?

Darkfiro7

Raging bull buster is Ranked ZM but you can get 5 piece from the ZM extra box (1500 crystal)
Same with Righteous The ZM extra 1500 box can give you 5 pieces.
It prefer you fill most of your ZM weapons to max as the 1500 box will refund you if it can't give you 5 pieces)

Ak buster is boss special crate reward (hard mode) in Crater Dawn

Darkfiro7

As of the new update The new ZM map can infact give righteous Shotgun pieces.