when going at low speeds on water the LVT(A)(4) (ZiS-2)'s gun will get a stabilizer like effect even when the tank doesn’t have one. (I might sound stupid but I just wanna talk about this little discovery)
Maybe because this one uses the same body of the LVT(A)(1) and may act it has vertical stabilizer on the water,
I’m not in-game so I can’t confirm right now, you could send a report to CBRS.