Actually, I mis-spoke.
The acceptance criteria for an M4A1 is a ten shot group with an extreme spread of 5.6 MOA. The misalignment of the sights from mechanical zero to intended POA is 5.2 MOA. The test ammunition must have a SD of between 3.4 and 4 inched at 600 yards.
The acceptance criteria for an M1 Garand was five shots within or cut a 5 inch circle at 100 yards, making the limit an extreme spread of about 5.3 MOA, with "ammunition of known good quality".
The poor initial accuracy of production M14s was the subject of much writing in the early 1960s. This resulted in a rather complicated accuracy acceptance procedure that took into account the average displayed accuracy of the test ammunition. But, this all was added to the specifications around 1965, after production ended.
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