Huh? The caliber is part of the platform.... I always thought the m1a was 7.62 or .308??? It's not known to be a super accurate round? It hits hard and the rifle is a military rifle meant for certain purposes and in which certain situations - would never be used unless there are no other options. It's meant to drop targets with one round in medium to medium-long range encounters with a relatively high-rate of semi-automatic fire. 7.62 is not designed to cut through wind.
So I guess maybe the 6.5 creedmore will maybe please scientific youtube gun critics and that could be their reason for chambering a version in 6.5