Bear Creek Armory has the 24" full upper. They are out of stock now, but I will be buying one in 6.5 Grendel
I would highly recommend you checking out some threads on 6.5 Grendel forum for BCA barrels and uppers before ordering from them.
http://www.65grendel.com/forum/forumdisplay.php?2-6-5-Grendel-ARs-and-Other-Semi-Autos