So I have been looking ar the JG AUG A3. http://www.evike.com/product_info.php?products_id=29826 I have a few questions. Looking on You tube and on various forums I see the the FPS range from 350ish to 450ish with .20's. I know there will be a FPS range but wow why such I large range? What is the stock spring on the gun and how easy is it to change? Thanks ahead for your help.