Originally Posted by Styrak
You don't need to upgrade them at all, they're great out of the box. However if you're willing to spend the money, then get the Toptech version.
Really? I found the CM guns to be low in quality. Gear thickness is different and so as the piston and piston head. The weird thing is, the new Top Tech looks exactly the same as the G&G and CM line. Don't know if G&G are using the same gearbox is all of their lines now, but I remember Top Tech had very much different internals than the others.