350 Is usually for indoors, around these neck of the woods 400 is the normal for outdoors.
Changing the FPS is relatively easy, once you know how, just a spring swap and you're golden Many videos on Youtube on how to do so for virtually every airsoft weapon ever made. Just search "M4/AK(whatever your weapon is) airsoft spring swap"
Just know, it's a limit not a goal. This cannot be stressed enough.
With the right parts, a 300 FPS gun will shoot pretty much the same as a 400 FPS gun.
Last edited by Forever_kaos; May 14th, 2013 at 20:10..