Lots of great information over on the M14 forum.
The M1A is a battle rifle that will shoot accurately out to 1000 yards. While it won't shoot bugholes, for all practical purposes,
the Supermatch should be capable of close to MOA performance (say 1-1.5 MOA) "on demand".
It is definitely capable of sub-MOA groups. But you'll be hard pressed to find anyone on the M14 forums
(a site dedicated to the platform) claiming they have a sub-MOA shooter.
I've held MOA out to 300 yards with my Springfield M21/M1A (essentially a Supermatch with an
adjustable walnut stock). My 2nd attempt/entry using my M21 of six groups of 5 rounds (30 shots) at 300 yards
averaged 1 MOA and is posted right here on the "Hide" in the 300 yard semi auto challenge. As Yogi Berra
said: "You could look it up." So far, I'm the only one who has attempted the challenge with his M1A.
http://www.snipershide.com/shooting...0yard-semi-auto-6groups-30round-shootout.html
I've also shot many sub-MOA groups out to 300 yards. But I wouldn't say mine is a sub-MOA shooter. I can rely on it
to consistently average around 1.25 MOA at 100 yards. I have held a little over 1.5 MOA all the way out to 600 yards for 10 shots - my best results. That's as far as I've shot it so far. My M21 and my SOCOM are the only .308 semis that I own and I am extremely happy with them both. If you like your SOCOM II, you'll love a Supermatch.
By the way, I use a Bassett Low mount on both my rigs and it is stable, doesn't work loose, and mounts in less than
2 minutes. A unitized gas assembly is universally recommended over on the M14 forum by builders and competitors as
one of the most important upgrades that contribute to accuracy. My understanding is that SAI blind welds the band to
the gas cylinder guide so a Supermatch should be "unitized".