For those interested, herer's the thread:
http://67.19.5.132/vb/showthread.php?s=&threadid=49263
The old shockers work quite well on Co2. In fact, some people back in the day preferred to use Co2 with their Shockers because the efficiency was way better than with air. One of their only advantages really, unless you like discontinued, old, blocky, heavy, humongous markers. Speed, weight and agility were never the Shocker's strongsuit, even back in it's hayday. They're getting fairly rare, as are parts and spares, and in our modern age of paintball technology, you can get much better markers for the money. In honesty, all things considered, you'd be way better off picking up an Ion.