The two previous iterations were all polymer and did not break at the buffer tube. This is basically just an evolution of the original design.
STarting in the early 2000's there was a company that I think changed it's name several times that was building the complete lowers and they would many times break at the tube or just in front of it. As I recall Cavalry Arms was the first successful version because they made their lowers out of polymer. The name of the company escapes me so I can't google it.
Anyway, the idea has come full circle and now that Brownell's has become involved I'm sure the finished product will now be successful.
kwg
I picked this up from a November 2008 entry on ARFCOM
STAY AWAY....
Hesse change to Vulcan. Then started Blackthorne. Now they are Velocity Firearms.
They keep changing their name but the lack of Quality stays the same.
I have redone many barreled upper that people got from Black thorne they seem to be put toghther by a monkey in the back room. And the monkey must have been drunk..