I'll start out by saying up front. I have no clue.
Now I will add my $0.02.
I have several DSA supplied barrels. I have zero issues with those. At my level in the game, I could care less who does what to whom. At the end of the game, my DSA products require little or no fussing around.
I apologize that I can not contribute to the question that began this thread, bu I thought that I might add my experience to the mix....
DSA is a very high quality vendor, with good prices and excellent customer service.
I recommend them to anyone, without reservations.
Not trying to derail the original thread. If anyone has had issues with DSA, especially since June 2011, I would like to know. That is the last time I ordered from them, and had no issues. Some AK parts, trigger group kind of stuff (AR), and some misc FAL bits. All very good, and all nearly drop-in.
Again, just my $0.02....