Those are the unicorns. usrifleteams is a great place to read up on how the M1A is not truly a sub moa rifle. There are other forums that also cover this. I do enjoy reading the "MOA all day" threads. There is a reason why most shoot an AR15.We form our opinions on what we observe.
Having observed several folks wearing out their M1A and M14NM rifles winning matches never needing them repaired or fixed for the lives of their barrels. That's proof to me some are rebuilt to start with much better than others.
Same was true with 7.62 Garands.
What is sad is how even the US armed forces keep going back to the M14 and relearn it is really a couple MOA rifle. When I was in the USMC got 1,000 M-14s from storage and did most of the tricks to make them real shooters to include putting a scope on. Long story very short. EOD went from having a very capable semi-auto (FA was removed) to having a very cool looking rifle that never lived up to the accuracy claims. Then the war happened so many jumped back on the M-14 band wagon and relearned that the M-14 is a battle rifle.
While you can polish a turd it is still a turd, and like most battle rifles several MOA is just the standard.
With all that being said if you have a M1A that shoots amazing and has held up over time you are one of the very lucky few.