I see in multiplayer people use single fire shot . How do we use ( activate) single fire in crysis 3 ?

I see in multiplayer people use single fire shot . How do we use ( activate) single fire in crysis 3 ?
There is a gun name Takedown which has primary single shot fire you don't need to activate... Scar has single shot... Press x [default] select single bullet icon, then press 2 [default], and single shot for scar will be activate...

Because for some reason using an underbarrel attachment forces you to physically remove the fire mode selector... lol...

Because for some reason using an underbarrel attachment forces you to physically remove the fire mode selector... lol...
Because attaching a laser sight under the barrel makes it impossible to attach reflex sight on the top of the gun

Because attaching a scope on top of the iron sights makes it impossible to attach reflex sight on the top of the gun



see where this is going?

But... but... what about when you... put a reflex sight on top of the scope that's on top of the gun...