CA M15A4 Sportline is a good gun
 

its really amazing! nearly compatible with all brands' M4's,even some Japanese made GBB(WA M4 GBB rail guard and stock totally interchangeable)

The gearbox is not that bad for its price,although with plastic bushings its still 100% upgradeable.

One thing not sure so far is the M203 could I simply go for a Dboy one??

OK.......

Mills0 and I have had completely different experiences with the things...

From warped gearbox shells, chipped piston rails and poor compression I dont think i'd ever touch a sportsline AEG ever again.