300 to 4-- fps, the .2s are fine. 400+ you need a heavier BB. I personally use SGM .29 bbs, but they also make heavier BBs.
As for the white/black combo...
I like the black BBs only in my SOCom pistol. I know where it always shoots, so i know where to aim. Sniping is a bit different. You kinda need to know where it goes to you can adjust on your next shot.. unless you know all the physics behind where the BB can go
I use the white dark-white colors in mine