Your not going to do much to it, and definatly not going to get any spring to give it more power for more then a few shots before the whole thing falls apart. Also, your not going to find piping in 6.04mm, and if you do, i bet the barrel in there is permantly affixed(if there is even a inner barrel)
Also, if the screws look plastic, and like the aint gunna come out is probably because they arnt screws, they are just for show and it all glued together :shock:
Save that money, and mow a few lawns, then get a GBB, they can be had for less then 80 bux