Well,
Here is my .00002 cents.
Imbel are good high quality receivers.
Well within all precision specs for FNFAL type Metric Rifles.
Top notch.
If my memory serves me correctly, I believe the lowers they have made are not completely heat treated, just specific areas. When they are finished you can see differences in the parkerizing.
The DSA uppers are definitely finished better than anything else made. They are actually better than original FN. Now some may take umbrage at that statement, but I have an original FN and compared to the DSA, it falls a bit short.
DSA does some beautiful work and that is fact.
Now, as far as the FN parts kits that Interordinance was selling. The imbroglio started by the ATF was this:
All machineguns must be TORCH CUT to be sold as parts kits. And I/O buggered up by NOT TORCHING but band sawing the receivers. Not only that, they GAVE the portions of the cut up receiver to you. ATF technical branch managed to band-aid one together and fire two consecutive shots out of it somehow and the fight was on.
Dram out