i don't own a complete NEA, but i do have 3 of thier lowers in custom builds. the first one is from "batch 12" and was almost a dream to build. one roll pin for the bolt catch was a bit loose, so in went an oversized pin.
the next 2 are from batch 13. (i assume these were machined out in 2013) i'm seriously wondering if i'll ever buy another NEA product because of them. they look identical to my first one, except they say "...nea. ontario canada....." now putting parts in, whole n'other story. takedown pins fit snug. good. upper fits flawlessly. also good. mil spec hardware however....not good. detent pins and springs won't fit. the rear takedown pin detent spring/pin location was moved 90 degrees, so its beside the fire select group. secured with the grip. neat idea at first. but there's no relief hole in the grip. and being a MOE+ you cant just drill a hole in it. second, ones you trim the spring, its too short to be used in anothr build should you need/choose to.
this hole was way undersized (maybe due to some of the nitrate getting in???) but it was also curved! i discovered this while i reamed out the hole. stopping halfway in when began to bind. i removed the bit and inspected the hole....that was oval??? a small piece of guitar string confirmed it. a curved hole. never saw that coming!
although not considered a "mil" part, ambi fire selector did fit in. but is a full 1mm too short to assemble and funcion.
now, i'm not sayin don't buy an NEA, complete or otherwise. just sayin proceed with caution. i generally use a cmmg kit, and the first one worked. i even stripped a few bits off two other rifles (of my own) for this build, and same. no go