So I've been looking at lots of guns lately most of them AEG's. But then I came across the WE KAC PDW GBB (http://www.tactical-center.com/items.php?c=2&sc=3&i=170
) and just instantly loved it. But it says it's rated for between 350 to 450 fps. I need it to be about 400 FPS. My question is how do I make the gun shoot a consistent 400 FPS?
It also says the gun takes Green gas/propane/CO2. Is the fps determined by the type of gas used in a GBB?
Sorry if this question is dumb, I'm new to all this. And just want to understand everything before I buy.