Originally Posted by Skladfin
Nope, can't switch lowers or uppers on KWA M4. They aren't TM compatible, it uses a different design. If you wanted to change the body, you'd have to go all out.
What are we talking about specifically? Dimensions or design? IIRC, both KWA and CA use tabs (like TM) to hold the upper down.
I personally don't trust those tabs, even in metal (airsoft) guns, so I'd never get a CA or KWA.