[-Otto-]

The problem is, most handguards are supposed to keep battery in it - therefore they are bigger than RS. That might be the reason why he would like to do that - and thats the reason I would like to put standard VFC grip to my AEG.

AEG offtop:
And it all depends on your AEG - Cyma is more or less copy of G&G, but there was modification needed to put RIS from cyma on G&G. Whats more, I was about buying JG (most likely, don't remember) grip for my Cyma, but when i have received photos of handguard mounted on cyma, I noticed that it is not parallel with the gas tube. So its not said that if it works with one brand, it will work fine with all of them.