I think they created some failure points with the breakdown style, and collapsible pistol grip, but having fired the weapons, it is a decent step forward.
Can you elaborate on the potential failure points? What could/should be done differently to make it better? This thread has caught my interest because this seems to be a really good way of carrying a 5.56mm carbine with a 16" barrel in a small, inconspicuous day pack. Separating the upper and lower receivers on a normal carbine leaves you with a pretty long upper unless you go with a 10.5" or 11.5" barrel. Sure, you could find a bigger day pack but that kind of defeats the purpose of blending into an urban environment.
I assume the USAF is using a standard M-4 barrel? Is that correct? What kind of railed hand guard is the Air Force using?
(EDIT: I spoke to a nice gentleman at the company named Mike. He tells me the USAF purchased BCM 12.5" barrels for their builds. The rail is from Midwest Industries, a G3 10.5" M-Lok. He cautioned me that the tube diameter on rails cannot exceed 2" or else the locking latches won't close properly. The QRB system itself adds another 1.4" of overall length to the hand guard. They've sold 3000 units to the USAF so far and about 1000 to civilians.)
The new BRN-180S shorty upper with a 10.5" barrel can be installed on an AR lower with a side folding non-NFA SIG MCX pistol brace. It also makes for a pretty convenient package. Take a look:
Overall length of the BRN-180s in the video link is 21" with the stock folded according to Paul Levy himself.
The longest length of the USAF rifle taken apart is probably around 15" and that would be for the upper and lower receiver with the stock collapsed. The detached barrel assembly is a 12.5" BCM barrel with an A2 muzzle device so add another 1.2" or so.
That is why the takedown rifle fits in the pilot's ejection seat bag that is only 16" long.)