I have just purchased a G&G CQB-R MAX and am slowly getting familiar with the gun and my options in terms of upgrades and modifications. I have contemplated upgrading the rail system to a Madbull Daniel Defense MKI8.
I stumbled upon this:http://miairsoft.proboards.com/index...y&thread=21643
It may or may not help you.
My charging handle does not open the dust cover, nor does my bolt catch work.
I have not attempted to remove the front triangle sight yet but close inspection says that it is possible to do so. YouTube - M4 AEG Front Sight Removal