The FAL is the best rifle for sniping, but the thick circle on the iron sights make it really hard to track distant enemies, I basically have to find them by aiming my sights elsewhere and then bring the crosshairs over them, which takes time.
Sounds to me like your utilizing an uneffective aiming method.
Locate the enemy and track without ironsights (hip fire), then if long range, pull up sights, and fire. You should never be spending time in ironsights trying to find enemies or aim at them. The reason is that when in ironsight mode, your movement and aim speed is piss poor.
I never look for enemies with ironsight. Ironsights should just be used to ensure accuracy after you have located and aimed for the guy in hip fire.