I've been putting one together since the end of June. I've got the barrel, I've ground out the ejection port on my upper, but I don't have a bolt or any ammo or.brass yet. Finally have a box of.ammo on the way but I'm still needing a bolt. I
If.your.building your own, get a 6.5 Grendel bolt from Rguns.  Ammo can be scrounged if youre persistant  brass will come around eventually.  If you're ordering an assembled upper I hope you're patient.