I purchased a full metal C-TAC M4 from buyairsoft and it was a decent transaction enough, It came like 3 days before the day they told me it would be in.
As far as i'm aware it's identical to VFC's and most likely built in the same manufacturing plant. One aspect I didn't care too much for was the piece to screw in the buffer tube is very short and made it a bit difficult to install a UBR stock and potentially other non-drop-in stocks. If you plan on modding the front end of this thing you might want to buy utility tool or w/e they are called. The C-TAC "pro" series (their full metal AR line) doesn't come with such. I went to town on the magazine when it came in and I stripped something on the magazine itself that holds it securely in the mag-well. I now need to hold down the plate connecting the mag release button to the mechanism inside to properly feed the stock magazine in (most likely my fault). Standard gen.2 gearbox with steel components and a very poorly chosen M130 spring for a market that is dominant in indoor fields. The nice thing about it being made in Taiwan and shipped in pieces to Canada to be assembled and distributed is that no part is glued on, Everything is hand tightened and ready to be swapped out. The barrel is 6.4 inches in diameter so it's recommended to swap that out for a 6.1 if you tighter um... "groupings" as i'll put it. I went AEG to try and avoid a gas block so I can install a Madbull DD Lite rail without needing to drill a piece to fit the tube and to my ironic surprise C-TAC's are equipped with the much needed dummy gas blocks. All in all I think it's decently build and the 7.4 lipo that it comes with is a nice finishing touch.