I use the crappy scope that came on the crappy clone VSR I was given It sucks for the most part, but so do airsoft balistics.
it is 3-9x`s variable zoom it holds its zero okayish, I use 3x`s for shooting or 5x`s to get a closer look sometimes even 9x`s.
If you want a fancy scope go nuts but it wont make a huge diference on hitting your target, Id kill for some iron sights on my BA it would be nice to have the option most times, i mean at two or three hundred feet how much zoom do I really need, and the crosshairs only line up at the point you zero the scope, and rear adjustable sight like on an m4 is sweet u work out what hight to set the rear at what range and you can tune it in in combat.
Dont get me wrong it is handy but not always, but yes id get something made for a real gun to put on a GBBR or itll be really useless im sure lol.
`Pardon my crappy sentance structure and spelling Im workin on it.
Also to those who are suggesting we buy snipers, human trafficing is highly illegal yall should watch what ya say. lol buy a sniper....rifle ya mean right?
EDIT:Cooney beat me