Hello! This is a annoying bug I discoverd while using the new AG4. If I shot a gun on the tank, and the tank gun gets destroyed by the fire effect then it falls of the tank but is still being used despite being detached from the tank. This is abit annoying but isn’t anything gamebreaking.
Got the same bug. PS4
I saw it as well on military Tank, but after destroying the mortar guns went silent.
Not specifically connected to the bug mentioned but still connected to the experimental AG4: if I view the weapon in my equipment slot it shows a bunch of characters but not a coherent name: ** Ööääööääöä.
This issue has been fixed internally and should roll out to you guys in a future patch 
Thanks for reporting!