The shorter action is a stiffer action in that it won't flex as much as a long action when fired . In theroy this makes a more accurate gun.
I know this is the "common knowledge" of bolt action receivers, but I've never seen any substancial proof that this is the case. I for one am not at all convinced that this is true to any measurable degree. I strongly suspect that this is a "flat Earth" theory, having been repeated enough times without rebuttal to be assumed as fact.
I would love to see someone build two rifles to identical tolerances with identical barrels cut with the same reamer, one built on a short and the other on a long action and really see if there is any measurable difference in accuracy.
Mike