How to fire a tank

[Ziyor]

I'm playing the tank destroyer showcase and the tutorial only tells you how to point the ♥♥♥♥♥♥♥ main gun at the target, not how to fire it (From the commanders seat). I know manual fire but that option isn't always there, even when i have the laser turned on. The bohemia wiki says to press 'R' but that just cancels the target. So wtf. I don't want to have to stop the tank and switch to the gunners seat just to shoot the flippin gun.

[Peasant]

from the commander's seat press ctrl+primary mouse button

[Gunter Severloh]

If there is AI in your crew in gunner's seat, you can press his corresponding F key, then press 2 for target, scroll through the list of availiable targets you know, and tell the AI to 3, 1 AI will fire at target at your command, just one way to do it.