引用自 Lil Jay：

What does the Alternative fire mode do for tanks and how do you activate it?

It is only available on specific vehicles. Vehicles that have it have a "second" main gun within the weapon selection tabs, with the description "alternate fire mode". It can be used by pressing the Alt Fire mode button, waiting for 5 secs, and the main fire mode will be disabled and alt fire mode will be enabled by using the " 2nd" Main gun and disabling the "1st"

Toggle off alt fire mode by pressing the button again and it'll reverse it in 5 seconds.

Vehicles that can use or have it include: Some IFVs, SPHs, and a few tanks.

I still don't get it. How? I'm trying to use it but gun just sticks and doesn't do anything

引用自 BeefInHisHood：

I still don't get it. How? I'm trying to use it but gun just sticks and doesn't do anything

You need to press "2" to access to the alt fire mode weapon, while in direct control. Press "1" to go back to main fire mode, but make sure you also press the toggle fire mode button first. So you have to do a bit of specific button clicking procedure to use them