i have a G&G GR-16 R4 Carbine. the exact model you are probably thinking of getting.
i have not gamed with this yet but i have had it for more than 4 months. I have the G&G with the gearbox stamped that says, 'G&G Armament' on the gearbox.
- it looks great out of the box.
- fires smooth, but a bit louder than the TM M4A1 S-System i had.
- It is a lightweight AEG compared to other full metal guns. this can be a plus for people who do not want to lug around a heavy rifle but still have a solid full metal AEG.
- There are NO rear body tabs, G&G has used lips to compensate for not having the rear tabs. The tab-less design makes it easy to switch out the hop-up unit and innerbarrel if you wish to put a longer inner barrel for when you attach a silencer onto the AEG.
Any other questions?
Personally, I find the ready-mag battery pack uncomfortable, and I prefer batteries stored in the rear of the gun. This is only a preference, other people may feel comfortable having it.
"SI VIS PACEM, PARA BELLUM"