Ive had a number of 308 AR's over the past ten years, and unless you are going pick up something like a GA Precision/les bear or something that was purpose built for accuracy, They are all going to be fairly close, maybe on average, one manufactures SS/Match rifle may be a tenth of a minute more accurate on average but not something really significant
308's over the years,
Armalute AR10 with LW barrel, Dont remember much about it.. dont remember any complaints
Built AR10 with 22inch Krieger, and adjustible gas system, awesome gun very accurate
Mega MATEN Build with Noveske barrel, could not compare it to my original AR10, but was great for the short time that I had it, Traded it for a Built 300WM in A4 Stock that i still shoot almost 10 years later after a rebarrel
LMT MWS with a number of barrels, 13.5 inch, 18 inch 308, and 20 inch 6.5CM SS Barrels are good sub minute barrels. The Stock CL was around MOA give or take.
I think the most impressive setup that i have had, is probably my 6.5CM MWS, Ive nailed some incredible groups with the barrel, and the velocity numbers appears to go subsonic around 1400. I am really looking forward to shooting it when i get home. I am not sure if I would call it the most accurate option available, but for what i am looking to do with it, its perfect.
I would suggest to anybody that interested in an accurate semi gas gun, find a gun with the features that they want and get out and shoot