I can't discuss contracts with you until I see the contracts, but for the most part, the specs listed on the ar15 blueprints circulating the net are fairly generous, by machining standards. Since it's absolutely pointless to hold tolerances any tighter than print, I SERIOUSLY doubt that anybody is working in the X/10,000" range except where absolutely necessary, and then it's absolutely necessary. That means threads, barrels, chambers and holes where called for. BASIC dimensions are their own artform.
The bottom line is, the part is in print and will function flawlessly, or it's not. If it is, I'll buy it. If it's not, then it's going back. If it claims to be milspec, it better be...if not, then it's a damn reject. Commercial specs are not so well defined.
The real test is in the post-machining processes. Are the parts adequately deburred and prepped prior to finishing? Are the threads clean? Etc, etc... Just about every complaint I have seen on the boards concerns fit and finish (then there is metalurgy), things that are discovered during break-in. Custom built firearms frequently require little or no break-in, but off the shelf stuff usually demands it.
Outfits that buy QC rejects and foist them onto the consumers at new prices reminds me of telemarketers preying on the elderly.
I have no problem with companies buying QC rejects and selling them to consumers at discounted prices, provided the consumer knows what he or she is getting, but that is not typically the case in the consumer market.