Ok, by that subject you should realize I'm new. This gun has a screw right behind the gauge, the manual calls it a regulator adjust screw. What exactly do I do with this? I'm assuming it regulates my CO2 to an extent, but how can I tell how much to regulate? The gauge doesn't seem to move when I adjust it, but now I've got the velocity adjust tightened all the way and it's only at 291 fps? Does anyone have any advice on this, and thanks.