I'm anxiously awaiting Aero Precision's M5E2 (Gen2) upper to be released. If it doesn't suit me I'll probably go with a Mega upper/lower combo. From there, probably a Krieger barrel, JP BCG, SLR adj block, etc...
Three days ago Aero told me they had 44 M5E's in stock. I would have bought one but I was not clear in my mind what rail/guard was congruent and they could not quickly explain. I got the impression, (and I could be wrong) that the M5E fit to handguard is proprietary. If anyone knows better please let me know.
I was altogether ignorant that the ones coming on line the end of this month were Gen2. The Aero website can be frustrating.
Aero makes two versions of the M-5 upper. One has an extension on the front of the receiver for their M-5 rail, they call it the "Enhanced". The other version is "normal" with the threaded extension, like you would see on any standard upper receiver. The Enhanced comes in their 5.56 uppers as well.
I have both, and either will shoot for you.
You can buy the M-5 rail separate, but they will ask you what type of upper you are using.
For a standard upper, the M-5 rail has a round barrel nut pretty much like any DPMS rail.tube, etc. The rail slips over the barrel nut and attaches with screws.
For their enhanced upper (with the rail extension), the barrel nut is proprietary, and goes into the extension under the M-5 rail. The rail attachs to the upper extension rather than the barrel nut.
