Recommend a 6mm ARC upper??

[khart1988]

One positive about buying an upper outright is that a good company should have their stuff sorted out. I'd still opt for an adjustable gas block if putting 6 ARC in an AR.

 

[rpol98]

Geissele supposedly makes crème-de-la-crème 6ARC rifles, I think they got a military contract, but they're way out of my price range. But i don't think they sell assembled upper receivers.

for example:
https://geissele.com/16gfr-6arc-rifle-ddc.html