Madbull Licensed Full Metal Daniel Defense Ver. 2 Receiver for M4/M16 Airsoft AEGs - Black

"I got this set for a long term build ive been working on so there are a lot of different parts from different manufactures going onto this receivers. the receiver set looks great coming out of the box but from then on ive been underwhelmed

Here is what fit fine:
Outer barrel Assembly-one lancer tactical, and another I dont know the mfg.
Barrel Nut
Rail-Madbull troy rail
Mag catch-Probably Lancer or G&G
Rail-seems fine. Ive mounted BUIS, a QD microdot and a 4x scope without incident

Here is what barely fits:

Buffer tube -I dont know the manufacture but it fit fine to loose on every other receiver ive tried. had to hammer it onto the receiver, haven't been able to get it off. Also there is no way to run a cord through the buffer tube to place batteries in the buffer or stock.
Hop up- the included hopup fit everything but I couldn't get it to feed. does not fit pro-win hop up at all
Gearbox-Matrix quick change gearbox. fits the lower receiver fine but I pretty much have to tap/hammer the upper receiver into place every time.

Here is what didnt fit at all:

Charging handle- Raptor clone sold here. unsuable. I was kinda able to slide the handle into the receiver but it immediately sticks and has to be hammered out. I tried placing the handle in other uppers I have and there is no interference so it is not an issue with the CH. I will have to sand the CH channel out a bit to put any charging handle in.

Some of this will likely be sorted out as the parts "wear in" (buffer tube, upper receiver fit and maybe the buffer tube) but that is only because the paint will scrape off over time (already started in most of the above mentioned areas.

Pros:
Trademarks looks cool
freehop up included

Cons:
tight to interference fit on a lot of standard parts.