I did a build with an NEA upper/lower and everything went fine. NEA has had some consistency and QC issues in the past and the new BCL 102 seems to be showing that they haven't gotten completely past that but most are fine and the ones that are not are usually dealt with quickly by NEA and any parts out of spec are replaced.
If you've already bought the upper/lower don't worry about it unless you have issues while putting it together (you probably won't).
If you haven't bought the upper lower yet I would suggest going with an Aero Precision upper/lower from Saskatoon Gunworks. There are also a few other lower price quality receiver sets available from some of our other site sponsors.
