I haven't kept up with the latest in firearms, so this may be old news...The QRB from Cry Havoc Tactical is an integral part of the new M4 survival rifle being issued to all USAF fighter pilots...It ups the survivability for a downed pilot in enemy territory over the usual pistol in a shoulder holster...
This all helps the gun fit snugly into the rest of the aircrew survival kit that goes under an Air Force pilot's ejection seat. The complete kit weighs less than 40 pounds and also includes signal flares, a flashlight, a medical kit, survival tools, and a life raft.
On the civilian side, it also makes it easy to change your AR-15 to a different caliber, such as 6.5 Blackout...Concerning accuracy, Cry Havoc says:
The QRB is able to retain POA/POI as the barrel still "head-spaces" off the stock positions (our tests have shown accuracy retained to less than 1 MOA of original rifle setup!).
I don't know if the folding grip is available to civilian purchasers though...I may have to get this for my Colt......Ben