Simply put, this gun is phenomenal. If you want a reliable, long range, and accurate gun look no further, provided you can tolerate a weapon that is slightly heavier and longer than a traditional M4/16 variant.
I've owned this gun for about a year now and have put a good 10,000+ rounds through it on both stock and upgraded parts. Out of the box the only thing that you may lament is it's relatively low muzzle velocity (mine came in around 350fps with 0.2's) but the hop up on this gun is amazing. Even with the low velocity I was able to adjust the hop such that with 0.25's I was still able to out range my buddy's JG M16 which was shooting around 400fps. But it was really the stock accuracy that first endeared me to this gun. It was a very satisfying experience the first time i fired it to see a little white dot appear above the front post and drop straight down at the end. The stock hop-up rubber is fantastic. Even once it wore in and developed a slight hook it was still very consistent; once you get used to it it can actually become an asset. Mind you that the hook is still only slight at range. Note that this gun can easily be upgraded to 400fps by only switching out the o-rings around the piston and cylinder head. The stock externals are rock solid, save for the heat shield on top, it's a little loose but I've never had an issue with it. The only reason you should replace it is for esthetic concerns. I recommend a large 9.6V battery, the stock is roomy enough to fit almost any sized battery.
However, this gun shines and has become my absolute favorite weapon when a few upgrades are put in. I have put in a new cylinder head (G&G proprietary), M120 spring, SCS hop up nub, a short high torque motor, and an AWS Pulse mosfet. With this set up and an 11.1V lipo I have a VERY consistent 1.83J of muzzle energy (nearly 450fps w/ 0/2's) and insane trigger response. I have disabled full auto due to my local field rules but the ROF is close to 20rps when bench tested. I'm able to get hits out to 200ft easy and during my last large game had 2 out at 250ft and 1 at 300. I highly recommend getting the G&G scope mount, though any real steal mount will work, and a good scope (I use a 1.5-6x and I couldn't imagine a better pairing).
The rest of the parts I've left stock save for the bucking which I had to replace with a madbull blue (still works great) when the stock one wore out and I have no plans to upgrade anything else. The stock shim job is decent, I only had to add a little to the spur gear (middle one), but your experience could vary.
Only downside are that midcaps are expensive and hard to find. I haven't had any problems with the CA's but their finish is painted on while the G&G's are actually blued. Also, the stock motor struggled a little to pull the M120, but it wasn't terrible. Other than that this is a tough, nearly perfect gun in my mind. If you want to get the best M14, get this one.
Midcaps expensive and hard to find (only G&G and CA's will work)
Flash hider has become slightly loose
Rating: [5 of 5 Stars!]