Can anyone tell me how to equip the the grenade thrower on weapon ( which key )?
U key is what it usually is to switch between the rifle grenades and normal shooting
yeah,
just like what @Rickyd123 said.
and than you load the grenade with R.
( which you have 3 of those before running out and be forced to unload the attachment by pressing U again. )
just to add to the above answers. if you change soldiers AI player will unequip it.
whatever key you map it to. i fiddled around with the key binds for a while and i found a pretty good setup for everything Optimal Keybinds