Have you tried scaling it down?
CrosshairScaling=1.0 to CrosshairScaling=0.0
Yes regardless of crosshair type and sizes which is weapon specific, crosshair scaling works on all weapons as its HUD specific command.
You might want to add to user.ini under [Engine.HUD]
[Engine.HUD]
CrosshairScale=0.0
CrosshairOpacity=0.0