Hi all i have recived my A&K m249 (Para version) .. And it has (as most of them) a trigger problem...
After doing som tech work (disassemble the hole gun) i found that most of the problem can be corrected by screwing the "trigger screw" just ½ turn down, and giving the electrical trigger (the rod sticking out the bottom of the bearbox) a small extra twist down (to compensate for the trigger screw)... This helps allot (but don't fix the problem) .... But a mosfet (yep thats all) installed (limits the amps over the trigger switch) that fixed it completely

I think the main issue with the gun and trigger is that when drawing high amps over the relative small 15-20 amp trigger switch it "burns" the 2 triggers together, and the spring is not always strong enough to pull it apart.... But installing a mosfet does the trick
When I'm done (I'm giving it a respray, and a full tuneup) I will post some more details and guides on my web page.
http://AirsoftTech.Dk/Guides.cshtml?Page=AKm249Para_Page1
Ps. Before adding in the mosfet, I was able to run like 8-10 full (2000 rounds) box mags throue the gun before the trigger started to develop problems. So out of the box it woks fine, but with time i can give you trigger problems ...
Another note: Cleaning the trigger contacts (fixing the problem temporarly) can be done by a few simple steps that most people can folow. 1. Take out gearbox (2 screws and push out a metal rod). 2. Remove the electrical trigger box from the gearbox (2 screws not need to open the box it self). 3. Pop open (use a flat head screwdriver) the electric box and clean off the small black burns .....
If you are planing to get a mosfet anyways (for upgrades or lipo usage protection) you can safely get the A&K version and save some money. If not be prepared to open the gun and clean the trigger every 10000 - 20000 bb's ...
Note that I have only tested one gun, so some may be worse some better .... But that's my eksperiance ...