GBB's are fun as hell, but not reliable. The amount of maintenance that has to go into one is insane. I know for a face two of my three AEG's will work no issue if I just randomly decide to go play airsoft.. and I haven't done any work on either of them (probably why they still work no issues....). GBB's, unless you dump a ton of time into them, generally do not work with that level of assurane. Of course there are exceptions, but very few.