[archy]

How about an AR-180 in .243?

That'd be the AR16, of which three were made, and which I saw and handled one of as a young acting corporal small arms instructor in 1966. It resembled a slightly oversized AR180, but with a beautiful burl walnut buttstock.

[Long Cut]

There are currently rumblings afoot that Armalite might explore that rifle again, if AR-180b sales and demand indicate that it would be profitable. The action seems easier to adapt to a more powerful cartridge than even the AR-15's.