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

"This is a pretty good receiver. It feels solid, and I haven't had any issues with paint scratching or anything after having it about a month. There however a few problems with it. My ares amoeba gearbox fit in it but it doesn't allow me to go all the way on to "Safe". It lets me go halfway into it so the safety does engage so it's not a huge problem. I've also had trouble finding mid-caps that fit it. I've tried G&P, VFC, and Hexmag. The G&P and VFC mags both fit and feed fine but in order to get them in, I basically have to slam them in. Getting them out is also a challenge. The Hexmag doesn't fit in at all. I tried jamming it in and I had to have my buddy hold the gun while I pulled the mag in order to get it out. For whatever reason though, I haven't had a single issue with hi-caps. So if you only use hi-caps then this won't be an issue for you. I, however, prefer mid-caps so this is a huge problem. Another problem I had was trying to get a buffer tube on. I had to hammer it on. I tried two different ones, both were a challenge. Once it's on, you're not getting it off. I also couldn't use the quick spring change feature of my gearbox. It simply didn't line up correctly. Besides that, it's a great receiver.
The hop-up it comes with is fantastic. It's almost as good as the ProWin hop-up I have in my other M4. It fits perfectly into the receiver and has the nice feature to add madbulls tracer unit to it which I am probably going to do. The bucking and spacer it comes with weren't the best so I swapped those out.
All in all this receiver is worth the money if you're okay with those small issues. I would recommend saving a little more and getting a slightly nicer receiver.