That is a possibility, but it is not for certain.
I don't mean to come across wrong-
Dad started shooting the 1000 yard matches in Texas with a .308. He had pretty bad accuracy problems until he worked up a load that was right on the verge of over stretching the brass. Since then, he said he's been doing well at the match. I believe he was attributing the accuracy problems to the bullet going subsonic. Maybe he just sped it up enough at the muzzle to keep it stable/spinning due to shorter flight time.