Ill chime in the on the GHK bandwagon here, brought in 8 of these guys last week and 2 of us have been testing ours pretty extensively since.
The gun is rock solid, no wobble, no creaks or cracks. The gas mags hold enough gas for over 100 rounds, something my KJW never could manage. I just fitted all magpul real steel parts, stock, grip, front rail and BAD lever. All fits super snug.
Plus the gun has all steel internals and im quoted by my sales guy as a 9,000 round break in period haha.
I got lots of spiel on my facebook if you want to read more about what we have tested.
www.facebook.com/b2airsoft
Cheers