A&K M4 Complete Metal Receiver for Tokyo Marui & Compatible Airsoft AEG Rifles

"Perfect metal receiver, fits a ares gearbox with no modification. cheap piece

"Echoing the experience of other reviewers here. I also could not fit a standard V2 gear box into this receiver without some modifications. Just needs a small Dremel cut off disk to remove a bit of excess material. I also did cut down the rear buffer tube quite a bit as well.

Not as thick as some of my other metal receivers, slightly lighter weight, but ironically, much sturdier. Seems to have really good machining on the parts. As the other review mentioned; there is absolutely no play between upper and lower. The two pieces smack together flawlessly.

Consider this a base for a custom build. This is likely not going to be a simple drop in part for most kits.

"It is a pretty standard receiver that needs some modifications to work. I had to remove some materials inside the front of the lower, where the lower portion of the hopup unit sits, so that the gearbox could be inserted. I also had to remove much of the buffer tube mount to fit a modern buffer tube. this receiver set comes with everything except for the selector plug. bolt catch release, trigger pin, body pins, charging handle, mag catch, and selector switch are all included

Pros:
cheap, sturdy, snappy selector switch, and flush top rail with most aftermarket rails. there is no play between the two halves of this receiver

cons:
needs some modifications and it doesn't include selector plug. selector plug is also proprietary compared to every other manufacturer, even retro arms. mag catch needs some modification to hold mags.

this is a good platform for a cost effective scratch build. i fitted a generic outer barrel and krytac defiance rail with no issues at all.