Just a thought experiment here...
I've always liked the AR-10. Being cheap I'll probably never buy one, but I could build one... sort of. It wouldn't have to be a real AR-10, just an AR-pattern rifle in .308. For that matter, why not .30-06?
Milling an AR receiver from billet has been done often enough. I've found several sets of drawings on the 'net.
As a first approximation, just stretch an ordinary AR at the magwell, widen enough to take an FN-D .30-06 mag, do any other fiddles needed. Use an ordinary AR trigger group, stock, pistol grip, etc.
That leaves the question of an upper. The AR uses a 1919-style barrel extension and a multipiece bolt, which wouldn't be all that difficult to upscale to suit the larger cartridge. The barrel extension and bolt head could be broached in the lathe, using the carriage or a tailstock fixture. Practically everything in the upper would have to be handmade.
Probably not worth the effort, but an '06 would be way cool.
You guys aren't helping. You're supposed to say, "Why would you want to do that?" or start a .308-vs.-.30-06 argument. Or at the very least, "what, you didn't know that's been done before, and you can buy the parts cheap?"
I found some, too. Apparently a couple of places make/made AR10 variants in .30-06. There's some discussion in this thread:
Cobb seems to have been the major player, though its web site is 404 now. Someone said they got bought out by Bushmaster. I found a picture. They also offered .300 Win Mag and .338 Lapua.
There's another thread here:
AR rifle chambered in .30-06 - THR
Why doesn't anybody offer an AR in 30-06??? - The Firearms Forum.Com
ahhhh they had them in 8x57 too!? lol my neighbor has been drilling AR's into my mind so i've been tempted to build one how with those screw together lower prints it would be simple to stretch the magwell to fit fn d 8mm mags, i've been wondering if a guy could just stretch an ar .308 bolt and carrier or if new ones would have to be made
A real retro 30'06 variant of the AR-10 is the WW-II Johnson rifle.
The lower isn't the problem....it and the upper can be streched....the tricky part is gonna be the legnthened bolt carrier......
You might not even have to lengthen the upper, or the bolt carrier. You might be able to stuff it into an AR10 by reconfiguring the FCG, shortening the buffer [to lengthen bolt travel], and moving the mag well back. Maybe delete the BHO to make room too.