Rack grade M1a's and Garands, neither are target rifles and I believe the acceptance criteria for factory M14's was that they were to shoot inside 3.5 inches at 100 yards.
I have a 1957 publication in front of me, for factory fresh NM 1957 Garands, fired with National Match ammunition, which grouped 0.6 inches at 100 yards in test barrels, out of a population of 665 rifles, 59.7% shot an average of 3 ten shot groups of 3.4 inches or less. I don't know how to calculate the number rejected, from the histogram, but rifles which grouped greater than the black, 4.2” were not sent to competitive shooters. That was a large number of rifles. The lowest average of 3 ten shot groups was 0.8 inches, the greatest average was 9.5”.
Garands were not glass bedded in 1957, that was a later modification. To me this data shows that a Garand, even in hand fitted stocks and metal parts, and carefully put together, was not that accurate. It took better barrels, glass bedding, all the later techniques to get them to shoot target grade accuracy.
Rack grade rifles are not target rifles. Even though I do not have acceptance data for service Garands, I am of the opinion that rack grade M14's were more accurate than rack grade Garands.
Target rifles are a different creature. If you perform all the match modifications, a Garand with a GI contour barrel is more accurate than a M14 with a GI contour barrel. In the 70’s a heavy M14 barrel was allowed in competition and the M14/M1a’s became the better target rifle in all particulars.
Garands in 30-06 kick more than M1a’s. A match Garand looses its tune sooner than a match M1a. M1a's are just easier to shoot.
Match Garand Targets fired in competition:
Rack Grade Garand shot prone in practice.
M1a, matched out except that barrel is a GI barrel, shot in competition.
