Got this gun used from my local airsoft store, and upgraded it moderately. Fires around 25 rounds per second. Currently runs on a borrowed 7.4v battery taped to the stock.
Internal upgrades include: CA Torque-Up Gears, G&P Piston, Silent Head Set, KM Head TBB, M120 Spring, M140 Motor.
I've used this rifle several times since I've gotten it and I've found it more than satisfactory. When I bought it, it was still stock and shot pretty well, but after moderate upgrading it shoots extremely well. I would definitely recommend this rifle to anybody. It may be too expensive for starters but for somebody with the funds it's a must buy.