[Hectic]

I have never seen any gun with the capabilities of a sniper. Guns cant hide or use stealth. They have no bushcraft skills. They cant outsmart their enemy. I think your looking for an aeg that can perform as well as a sniper rifle.
Either an m14 or a psg1 but either way you most likely wont be able to use itaove 400fps if your lucky and its semi auto locked you may be able to use 450fps but youll be limited in ammo weight with that velocity (.36 would likely be as heavy as you can go and thatll be pushin it at 450fps) on top of thst an aeg will never be as consistant as a bolt action. Its just the nature of the beast. Build a good bolt action and carry an mp5k/mp7/mp9 or mac11 or mini uzi then you can go assult when you need.