Nothing except for the hopper adaptor clip & remote or/and bottom line.
Accurate - Very! even with dimpled paint!!
Distance - holy crap, this gun shoots far!
Noise - 1 loud MF...I love loud guns... Mine received the name "The Cannon"
Ballbreaks - rarely (3000 rounds, 1 ball break - easy fix, lightly coat the inside of the magazine with rifle oil inside)
Weight - very light
Feedrate - Fast, I unloaded a magazine in alike 2 seconds - even semi is fast!
If you bend a few pins, just bend them back into place with your thumb!
Maintenance isn't that hard - Just keep that manual near you... You don't really touch much on there.
And people won't stop asking questions about it!
Expensive, easy to break, front loader kinda sucks (port needs to be open more-I think the newer version has that done already, not sure)
Most fields won't let you play in full auto (luckly there is a screw hole to turn off full auto) But you don't really need it! :)
I wouldn't reccomend this gun for the beginner. But if you take apart guns all the time and you want something fun, get this one!