Most recent 6.8 spcll. BCM upper receiver, ARP barrel, Aero lower receiver. I am thinking of rattle can job. It's hard to commit to though. It will get a Swampfox1-10 in the near future. The red Ambi safety will get the axe as soon as I order a V7 black one. Probably get a different lower receiver as soon as I can get the one I want. The fit on this one is great but you know how it is. It's not done until you get it exactly right.